Adorably Precocious Child: As seen in Chapter Zero, he is quite perceptive despite being only seven years old when he manages to figure out Kuronagi (who he only seen once and that was when he's at near death mind you) was the one who saved him. Kuronagi likewise is both shocked and impressed by it.
Adorkable: Oh he definitely is. It's pretty much a staple for any Chronicles Collection protagonists by this point.
All Of The Other Raindeer: He used to be this during middle school in part due to being the only non-human at his school. It doesn't help the fact that he ended up being a Shrinking Violet due to Laser-Guided Amnesia.
All-Loving Hero: Roku is pretty much the definition of this. There is no one, and I mean no one, he will not try to befriend or at least being kind to any other person regardless if they're being a dick. There's a lot of characters in the Jerkass spectrums (i.e. Vanitas, Cross, and Mukuro) who actually gets a long with him. Even the most hostile villains aren't exempt for this as Roku will feel sympathy for them, especially those who had tragic backstories (i.e. Teru/Hazama). In fact, he's so loving that he is actually incapable of feeling any hatred to anyone, the worst thing he could do is feeling pity on them.
It's revealed later on to be a downplayed Deconstruction of it. His incapability to hate someone is actually his form of disability as a Half-Blood, as according to Word of God viewed it as such by the Pureblood Espers as even they find it unnatural. Roku even points out that it gives a lot of problems with his relationship with his own uncle as he is frustrated that he couldn't hate him in spite of what he did.
Ambiguous Situation: His relationship with Kuronagi is this for most parts of the whole School-Side Chronicles, particularly during Part I (Pre-Timeskip) of the series. While it is explicitly shown that Kuronagi has at least an affection for Roku and would stop at nothing to protect him at all even if it means damning the entire world, it's never once hinted whether he felt for Roku is either romantic or platonic or even familial. The same goes to Roku as his feelings for Kuronagi are often flipped between romantic or familial. A lot of their interactions goes towards the romantic light especially given Roku's reaction whenever someone teases/speculates him and Kuronagi being a couple. Not helping the fact that Kuronagi himself will occasionally acts like a Crazy Jealous Guy unlike how Vanitas does. Eventually, Word of God confirmed that both Roku and Kuronagi's relationship is very much romantic and they are (technically) the series' Official Couple.
Badass: As on par with the series, Roku is no slouch in fighting and is one of the most powerful character in the entire School-Side Chronicles. He only loses out to the very much broken and overpowered characters like Kuronagi is. He is also the most powerful out of all the Chronicles Collection protagonists.
Badass Adorable: In XBlaze, he's only 13 but still kicks ass as much as is his 17-19 years old self. Even when he is grown up he's still very much this due to his Adorkable personality.
Badass in Distress: By the Revenant Souls series and onwards, Roku ends up as this most of the times due to his status as both the "Will of Azure" and "The Key of the Universe". The main conflict in Reunion Fiction is the antagonists trying to catch him as "The Key of Restoration" to bring forth the Harbinger of Death, Hades Izanagi.
Handicapped Badass: By Esper standards at least, as Half-Blood Espers are most often to have "disabilities" compared to the more "normal" ones; in Roku's case it being his incapability to hate. Not that it interferes with his fighting abilities.
Took A Level In Badass
Underestimating Badassery: A lot of the enemies tends to underestimate Roku due to him being too "soft-hearted" and boy do they tend to pay for it. Illua and Iris are the best example for this.
Barrier Maiden: He is the "Key of the Universe" and is responsible for the state of the world's balance as if he were to die then the world will plunged into chaos in an apocalyptic scale, as shown by the Origin Timeline's state following that version of Roku's suicide. Reunion Fiction explained it more in detail that Roku is one half of the "Key of the Universe" as the "Key of Restoration" being this to Yuto's "Key of Destruction" status as an Apocalypse Maiden.
Berserk Button: Hurting the people he care about, especially his friends, is a surefire way to get Roku angry. Insulting Kuronagi is also one, as Virgillius learns the hard way.
Caius, his uncle, is basically a walking button for him throughout Chronicles of Miracles, as a result of Roku's mixed feelings of anger over the former's actions of murdering his entire classmate after the "rabbit" incident in the past and frustration over not being able to hate him. This disappears in the end when Roku eventually has the heart to forgive him.
Bi the Way: According to Word of God, Roku doesn't really care about someone's gender as long as he could love them.
Big Damn Kiss: With Vanitas in Dissidia School Side III, following the latter's rescue from Virgillius' Lotus-Eater Machine of his traumatic past. Needless to say, the latter is too shocked and embarrassed by the action that he ended up hitting Roku for it, unsurprisingly.
He eventually has one too with Kuronagi at the end of Reunion Fiction, cementing their Relationship Upgrade.
Big Brother Instinct: He is this towards many of the younger characters, particularly Rini and Misato.
Big Brother Mentor: He tries to be one to Rini with... varied level of success. He is also this to the other Chronicles Collection protagonists during crossovers by virtue of being the oldest.
Blood-Splattered Innocents: Happens to him after witnessing his uncle massacring his entire classmates as seen in the flashback in Chronicles of Miracles. The incident ends up being one of the catalysts for his (supposedly) massive hatred for him.
Break the Cutie: Things do NOT go well for him at all. Chronologically, he was the only survivor of The Great Disaster when he was only seven years old, finding out his First Love being turned into a "Doll" by the enemy, ended up losing most of his memories after losing control of his Azure Powers, getting horrifically bullied by his classmates and then seeing his uncle massacring them, the entire first two seasons of Dissidia School Side series (including witnessing the Second Great Disaster), meeting his Yandere First Love again, getting Mind Rape by Hazama, being told he is the Barrier Maiden, and so on so on. Needless to say, he didn't come out of all of this entirely unscathed (Thanks a lot Hazama),
Butt Monkey: Downplayed but he is very often ends up suffering through Vanitas' increasing abuse due to the latter's Tsundere and Crazy Jealous Guy tendencies, which is all Played for Laughs. There's also the fact that Rini doesn't have any respect for him at all despite him trying to be a good senior to her.
Chaste Hero/Celibate Hero: On one hand, he is a Clueless Chick and Dude Magnet and on the other hand he's not completely Oblivious to Love; as seen with both Vanitas and Lambda. That said, he doesn't really had much time to think about dating anyone. This goes to the extent even when he does have a Relationship Upgrade with Kuronagi, they don't... actually date each other normally for good reasons (That said, it is explicitly clear they're both exclusive for each other).
Character Development: Starts out as a Shrinking Violet Reluctant Warrior before growing into a more confident, mature person and less reluctant at fighting. He is also noticeably becoming more cheerful and energetic much like his younger self although still touched with maturity, this carries over in his Crossover appearances.
The Chosen One: He is both the Chosen of Fate and the Will of Azure.
Chronic Hero Syndrome
Clueless Chick/Dude Magnet: Kuronagi, Vanitas, Lambda/Mio, Cross and Satomi all have feelings for him and he's the unfortunate attention of Nue's and Junko's obsession. However, only Kuronagi, Vanitas and Lambda/Mio are the only one he actually noticed and Kuronagi ends up being the only one he chooses in the end.
Combat Tropes
Blade Spam
Cool Keyblade: His signature Keyblade, Oblivion; which is different than the one Roxas have.
Elemental Powers: Every Esper have an affinity with certain elements which is later reflected into their Esper Magic. Roku is one of the few Espers who has more than two Elemental Affinities at three: Water, Wind, and Lightning. He is also learned variety of other elemental Black Magic spells outside his affinities as well as the White Magic's Holy line spells.
Blow You Away: His main Elemental Affinity and the element of his Eidolon, Syldra.
Making A Splash
Light 'Em Up/Holy Hand Grenade
Shock And Awe
Everything's Better With Spinning
Flash Step
Healing Factor: All Espers have the innate ability to regenerate wounds, however Roku has the distinction of his Healing Factor more powerful than other Espers by able to regenerate heavy wounds in a minute while it took a normal Pureblooded Esper a few days at the least to recover fully. This is because of his innate Azure Arc ability. Taken Up to Eleven with Azure Arc's Azure Heal which heals instantenously.
Healing Hands: Learns the Cure line spells.
Lightning Bruiser: Initially appearing more like a Glass Cannon, with high speed and powerful truck-hitting attacks, however his unnaturally fast Healing Factor (even without the Azure Arc's power) made it easily for him to tank out attacks at a more limited times. By Dissidia School Side III however, he started to fit into this role more perfectly and becomes more and more broken once he learns to control his Azure Arc powers.
Limit Break: Thunderstorm, his strongest and most iconic finishing attack. Roku starts by summoning a tornado that carries the enemy in mid-air before followed by a Lightning-enhanced Speed Blitz which is later finished by one final lunge attack that slashes through the enemy. In the Ultimate Arena series, it serves as his EX Drive.
Magic Knight
Red Mage: Learns Esper Magic, Black Magic and White Magic.
Speed Blitz
Spellblade
Story Breaker Power: Azure Arc, the strongest out of all the Azure Magic. It includes a variety of abilities that are downright broken which includes an Armor-Piercing Attack (Azure Burst), Healing Factor (Azure Heal), Teleport Spamming Speed Blitz (Azure Flash Pressure) and a destructiveSuper Mode (Azure Kain); and that's only the most seen ones at all. It prevented from being too broken as the Azure Arc causes Roku to tired out as it is taxing on his magical power (as being an Esper he needs Magic to properly live) and even when he is finally able to control and learn it better, he mostly uses the few basic and "weakest" of its attacks (Azure Burst) or its passives (Azure Heal) thus preserving it for the harder battles.
Summon Magic: Each Esper has their own Summon Beasts called Eidolon ala Final Fantasy XIII which they can summon at will. Roku's Eidolon is the Wind-elemental Syldra, the Dragon of Storms.
Super Mode: Azure Kain.
Super Speed
Sword Beam
Throwing Your Keyblade Always Work
Weapon Twirling
Cooldown Hug: Gives one to Vanitas in the final arc of the first season of Dissidia School Side, to Cross in Continuum Shift and Retrace Phantasma when he is about to lose control of his Azure Engine, and to Roxas during his breakdown in Chronicles of Fate 2 -Final-. He also receives one from Azure during the Virgillius' Labyrinth arc when he almost goes crazy from witnessing Vanitas' traumatic past.
Covert Pervert
Cry Cute
Curb-Stomp Battle
Cuteness Proximity: Squees and tries to glomp on anything he thinks cute of. Keyword "thinks", as his definition of cuteness tends to be really...strange.
Dark And Troubled Past
Deadpan Snarker: Post-Character Development, Roku now does it very often particularly when he ends up being the Only Sane Man out of his friends.
Declaration of Protection: Gives one to Vanitas and Lambda and receives one from Kuronagi, Vanitas, Cross and Lambda.
Defeat Means Friendship
Despair Event Horizon: Nearly crossed into this after the Second Great Disaster before Tidus snaps him out of it.
The Determinator
Deuteragonist: In the overarching School-Side Chronicles story, he is the deuteragonist to Kuronagi's protagonist status as he has the most development next to the latter, him being both the MacGuffin Boy and Barrier Maiden and later as Kuronagi's Love Interest. In the Chronicles Collection collective universe, he is the representative Protagonist of School-Side Chronicles with Kuronagi as the Deuteragonist.
Disney Death
Dogged Nice Guy
Embarrassing Hobby: He considers his Violin playing as this, at least when around other people in part because he can't handle the praises they often gave to him. He does swallows his pride when he helps in performing as seen during the Grand Festival arc.
The Empath
Even The Guys Want Him: Vanitas and Kuronagi are his Love Interests. Cross is hinted at times had a crush on him and, according to Zidane and Bartz, Roku has both female and male fans in the school.
Expy
Fighter, Mage, Thief: The Mage to Cross' Fighter and Kuronagi's Thief.
Foil
For Happiness
Forgotten First Meeting: With Nue/Mio and Cross in Ultimate Arena due to his Laser-Guided Amnesia in XBlaze as a result of him losing control of his Azure Ac. Subverted with Kuronagi as he still remembers him despite said amnesia.
Fountains of Expies: Much like Kuronagi, Roku starts the archetype of the "selfless all-loving hero" in the Chronicles Collection Universe. Ironically, it's not the Protagonists who are expies of him, the closest thing would probably be Airi, though they do shared a bit of his Friendship Freak personality.
Freak Out: Has one during Virgillius' Labyrinth arc when he saw the memory of Vanitas/Agito murdering his Abusive Mother before commiting suicide.
Friend to All Living Things
Friend to All Children
Friendless Background: Even before the bullying, Roku doesn't made any friends due to busy taking care of the depressive Rukia at a young age. Tidus is the first friend he ever made, apart from Kuronagi.
Friendship Freak
Fusion Dance: With Yuto of the Involuntary The Composite and Fusion Dissonance as Hades Izanagi, the Final Boss of Act 2 Arcade Mode and Story Mode of Reunion Fiction.
Generation Xerox
Genius Ditz/Ditzy Genius
The Gifted: Despite being a "disabled" in the Espers eyes, they do acknowledge that he is one of the special ones due to having three Elemental Affinities and outright talented in both the physical and magical fighting aspects. This is due to his status as the Will of Azure.
The Glomp: Often does this to Vanitas and Cross, especially during his Cuteness Proximity moments much to their dismay.
Good Is Not Soft: Roku is a saint but that does NOT mean he won't hesitate to fight and would show no mercy to people who hurts those closest to him.
H-P[]
Half-Human Hybrid: He is a Half-Blood Esper much like his mother and close relatives.
Harmful to Minors: He was seven years old when he got caught in the First Great Disaster. Had Kuronagi not saved him, Roku would've died.
Headbutt of Love: Often does this with Kuronagi to show how close and intimate their relationship is. The most memorable ones are when Kuronagi saying farewell and promise to meet again in the final episode of Dissidia School Side III, Roku reassuring Kuronagi that he won't leave him in Chronicles of Fate 2 -Final- and following their Big Damn Kiss in Reunion Fiction.
The Hero: Of Dissidia School Side series and the representative of School-Side Chronicles.
Heroic BSOD
Heroic Lineage: He is the descendant and successor of the first Chosen of Fate, Reol Klein.
Heroic Sacrifice: Does this in Dissidia School Side II, Revenant Soul and Continuum Shift though thankfully it didn't stick very long. He almost does this during Chronicles of Fate 2 -Final- but Kuronagi put a stop to it before he could.
Heroic Self-Depecration: Roku doesn't think very highly of himself as he tells Vanitas that he isn't sure that he could succeed his ancestor legacy as a Chosen of Fate. Needless to say, no one is having any of it; especially for Kuronagi and Vanitas.
Heterosexual Life Partners: With Tidus.
Hidden Depths: He is a talented violinist though he doesn't like it when people bring him up since he couldn't handle the praise and doesn't like the spotlight.
Identical Grandson: He is the near spitting image of his ancestor, Reol.
I Just Want to Have Friends
"I Know You're In There Somewhere" Fight: In Continuum Shift, when Oz manages to take over Kuronagi and attempts to kill him just to make Kuronagi suffer, Roku desperately calls to "Nagi" to wake up while trying to defend and avoid against Oz and refusing to even fighting back despite everyone's pleas. Thankfully, he succeeds.
Immune to Fate: As both a Chosen of Fate and the Will of Azure, Roku isn't affected by anything the Fates thrown at him which changes a lot of outcomes for a lot of characters, particularly the Ayanami siblings. In fact, he is the one who can control and rewrite anyone's Fate.
Insane Forgiveness: No matter how much of an ass or monstrous someone was, it is guaranteed that Roku will forgive them despite their wrongdoings, bonus point if they were already sympathetic to begin with. That said, he does believe in Forgiven, but Not Forgotten and make sure they do repent on it. The only person he doesn't seem willing to forgive is Iris, who is the Big Bad and a Complete Monster.
Interspecies Romance: With Kuronagi, one of the 13 Wizards and a former revenant soul of a toy rabbit.
I Owe You My Life: How he feels towards Kuronagi as he was the one who saved his life after the First Great Disaster happened. Which is the reason why he hates when people started to insult or degrade his name for it.
Irrational Hatred: Towards his uncle Caius for massacring his classmates despite them being the ones who bullied him relentlessly. Doubtly so when Roku knew that his uncle meant well and was trying to protect him but he refuses to even humor the notion. It's later revealed that it mostly stems from Roku's frustration over his "disability" preventing him from getting angry at his uncle's actions and only when he finally made peace with it that he was willing to forgive and apologize to him.
It's All My Fault
I Want My Beloved to Be Happy: To Mio come Retrace Phantasma. He already moved on from her after finding peace that they could never be together knowing that Mio already suffered enough as it is. Which is the reason why he left her alone when he saw Mio alive at the final cutscene according to Word of God.
I Will Wait For You: For Kuronagi, due to the latter's role as the Wizard of Time preventing them to be together at most times.
Keet
The Kirk: To Cross' McCoy and Kuronagi's Spock.
Laughing Mad: Happens to him as he Freaks Out from witnessing Vanitas' memory of his suicide in his previous life.
Laser-Guided Amnesia: XBlaze reveals that Roku ended up losing most of his memories as a result of Kuronagi forcefully sealing his Azure Arc after losing control of it. This actually explains the inconsistencies of his behaviour between the prequels and the Dissidia School Side series.
The Leader: For the Seven Chosens of Fate. He also served as a de-facto Leader with the other Chronicles Collection protagonists during Crossovers.
Like Brother And Sister: Develops one with Rini. Even if what she said otherwise.
Living Emotional Crutch: He is one for Kuronagi. After years of being broken and jaded as a result of Frederica/Elluka's actions throughout his life, Roku is his only reason to kept living after finding and saving the boy from dying due to the Great Disaster (which he unwittingly had a hand in it) as he felt that he was the only way that Kuronagi doesn't completely give up on humanity and the whole world as whole. Kuronagi does realize that his attachment to Roku is unhealthy to an extent but he admits that he doesn't care because meeting Roku was the first time he did without being manipulated into it.
Love Makes You Crazy: Briefly dips into one after witnessing the memory of Vanitas' Dark And Troubled Past with his suicide being the last straw. Thankfully, Azure is able to snap him out of it quickly and reminding him on the reason why he saw the memory in the first place.
Love Martyr: For Mio in the Ultimate Arena series, particularly during Requiem Shift. He felt so bad for forgetting her and blames himself for her turning into Nue that he desperately tries so hard to bring bad her old self despite everyone, particularly Cross, telling him it was impossible. He does gets over it when he reluctantly has to Mercy Kill her knowing that the Mio he had loved already gone the moment she turned into Trinity.
Luminescent Blush: Whenever he gets easily shy, his cheeks gets easily redden. This is particularly best shown whenever he has his moments with Vanitas and Kuronagi.
Magnetic Hero: Roku is very charismatic enough that it draws a lot of people (whether they are good or bad) into joining his side as they are attracted to his kindness. Word of God even confirms Roku is the most charismatic compared to other Chronicles Collection protagonists.
Manic Pixie Dream Guy: Towards Vanitas, much to his chagrin. Though, Roku does succeeds into making Vanitas much more defrosted regardless of the latter's denials. He is also one platonically towards Cross in the Ultimate Arena series, particularly during Requiem Shift and Continuum Shift.
Mean, Nice and In-Between: Roku is the Nice to Cross' Mean and Kuronagi's In-Between.
The Messiah
Mind Rape: Teru/Hazama puts him into one in Cross' Bad Ending and canonically in Requiem Shift, though in the latter part he was thankfully saved by Kuronagi before it gets worse.
Morality Pet: He is one for Kuronagi, Vanitas and Cross. Roku is pretty much Kuronagi's entire world and his reason to live to the point he wouldn't hesitate to burn down the whole world down if it meant that Roku is safe; Vanitas considers Roku being the first person who treats him with kindness and saving him from the trauma of his past; Cross started to soften up more thanks to Roku's help and felt indebted for him saving him during the events of Ultimate Arena.
Morality Chain: For Vanitas, who admits that had he not met Roku that he would probably ended up being a sadistic and emotionless monster for his whole life. There's also the fact Vanitas would lost control of himself if something were to happen to Roku.
My God, What Have I Done?: Has this reaction once Cross calls him out for treating Lambda as a Replacement Goldfish for Mio which prompts Roku into apologizing and turning his behaviour towards her as a result.
New Transfer Student: Introduced as one in Dissidia School Side. Interesting to note that he actually lived in Cornelia City before but had to transferred back and forth as a result of both his mother's jobs and the trauma of the Great Disaster.
Nice Guy: Roku is by far the nicest out of all both the School-Side Chronicles and the Chronicles Collection series. Not even characters like Misato, Sora, Kirito, Airi, and Satoshi are a match for his kindness.
Beware The Nice Ones: That said, just because he is an absolute saint doesn't mean he is harmless. In fact, making Roku angry is one thing you would NOT want to.
The Nicknamer: Calls Vanitas "Vani" or "Vani-chan", which the former finds it an Embarrassing Nickname; gave Mai her "name"; and the one who calls Kuronagi his Affectionate Nickname, "Nagi".
No Sense of Personal Space: Does this to an embarrassing degree towards Vanitas, resulting him getting a beat down by the latter so so many times.
Not So Above It All
Not So Different
Obfuscating Stupidity
Odd Friendship: With Mukuro Rokudo during Crossovers which is lampshaded to hell and back by a lot of characters. Roku is the only one who is constantly nice to him, though he won't hesitate to call out the latter's usual trolling, and at worst only tolerated him. Mukuro in turn is much more comfortable with Roku and the latter is one of the few characters where Mukuro isn't a Jerkass too.
Official Couple: With Kuronagi.
Only Sane Man: At times, particularly with his fellow Seven Chosens of Fate companions. Though nowadays, he is mostly Not So Above It All.
The Pollyana
The Power of Friendship: A fervent believer of this. In fact, it was the reason why he managed to access his Azure Kain Super Mode for the first time during the finale of Dissidia School Side III. Also crosses with The Power of Trust when it comes to Vanitas and Cross.
The Promise: Made one with Kuronagi at the end of Chapter Zero, which they promised not to forget each other no matter what if they meet again. And Roku did kept up his promise come Dissidia School Side III.
Q-V[]
Red Oni, Blue Oni: He is the Blue Oni to Tidus' and Cross' Red Oni.
Relationship Upgrade: With Kuronagi in Reunion Fiction.
Scars Are Forever: Has a scar on his forearm as a result of Kuronagi transferring half of his Azure Arc to Roku in order to save his life after the Great Disaster.
Screw Destiny
Shrinking Violet
Ship Tease: With Mio/Lambda, Vanitas and Kuronagi.
Mio/Lambda:
Mio was his First Love as a child and he is outright horrified and guilt-ridden finding she was forcibly turned into as Nue by Teru/Hazama's machinations. A lot of Ultimate Arena and Continuum Shift's main problem has him being a Love Martyr towards her and ultimately he was forced to realized that she was beyond saving and has to Mercy Kill when she became Trinity to save her.
In Revenant Soul, he eventually find out that a remnant of Mio's original soul is left inside the Elevent Tenshi Unit, Lambda and decided to befriend her as his personal atonement for not being able to help her. However, Lambda being unable to emote due to her status as Konoe and the Seventh Sector's "weapon" caused him to lash out on her for not being "his Mio" causing her to be afraid of him once her emotion started to act up. It's not until Cross calls him out on his behaviour that Roku realized how wrong he is to treat Lambda as a Replacement Goldfish leading to him reconcile with her and prompting his Declaration of Protection of her. In turn, Lambda eventually develops romantic feelings for him to the point she sacrifices her life to save him from Trinity's attack and giving him her Dying Declaration of Love; her death results in Roku going Unstoppable Rage and defeats Trinity with his now controlled Azure Arc power.
In Retrace Phantasma, Lambda was resurrected and fully in-tuned with Mio's soul thaks to Konoe's and Elluka's actions. She vows throughout the game to find Roku and protect him from her "other self", Nue. They both have a heartfelt reunion when they meet and knowing that Lambda wants to stop and reunite with Nue, Roku doesn't hesitate to help her with it. When they finally defeat Nue in her breakdown and insanity, Lambda eventually comforts her "other self" and reconciles with her before fusing to turn back into Mio. Mio, knowing she doesn't have enough time left, tells Roku that he doesn't have to wait for her ever again and moved on happily with his life ending with her confessing her love one last time for him before disappearing. However, by this point Roku had already moved on from his feelings for Mio (see I Want My Beloved to be Happy Above) and developed one for Kuronagi and according to Word of God, left her alone when he saw Mio still alive in Kagutsuchi Station during the final cutscene in Retrace Phantasma.
Vanitas: Roku started to grow closer towards Vanitas upon learning how the latter wasn't as cruel as he thought he was and doesn't back down no matter how many times Vanitas tried to push him away. Vanitas on his part doesn't think he deserves Roku's kindness due to how he treated him in the begginning and is horrible at showing his feelings towards him, often in hilarious results. Despite that, they do started to become close friends as they get to know each other and when Vanitas (and the rest of Capriccio Farce) came back in III, Roku is overjoyed the most upon reuniting. They became much closer once Roku finally learns about Vanitas' Dark and Troubled Past and vows to protect him as much as Vanitas does for him leading to an actual Love Confession that makes the latter flustered to no end with predictable results (that said, Vanitas does tell him that he reciprocates the feeling). Despite both of them already confessing each other feelings, they don't actually officially get together; especially with Kuronagi starting to come back to Roku more often making things more complicated than it is. Realizing that Roku is conflicted about choosing between the both of them, Vanitas eventually ends up pushing him towards Kuronagi instead since he knows that Kuronagi is clearly Roku's most important person and he wants Roku's happiness above all else. They ended up being close friends in the end even if Vanitas still acts like a Crazy Jealous Guy sometimes (often with Kuronagi joining him).
Kuronagi:
Ever since the Kuronagi saved his life when he was little, both he and the Wizard formed an unbreakable bond with each other despite only having a little time to getting to know each other. They both made a promise to each other that both of them will remember the other when they meet again in the future. This promise is so important to Roku that, despite his Laser-Guided Amnesia unintentionally caused by Kuronagi himself, he still remembers the Wizard once they meet again face-to-face in Dissidia School Side III. Needless to say, Kuronagi didn't expect that to happen and eventually resulting them to reconcile properly in the end.
Kuronagi considers Roku as the "light" that saved his life after nearly crossing the Despair Event Horizon as a result of being used by both Hazama and Frederica/Elluka. As a result, Kuronagi considers Roku his entire world and the only reason he actually gave a damn about keeping the entire world (and the Multiverse) safe outside the latter being the Barrier Maiden and out of necessity, even straight-up admitting to Kaito that if it weren't for Roku that he will gladly let the entire world burn down for all he care. Roku in turn also considers Kuronagi his most precious person in his life as he admits without him, he felt rather lonely after not seeing him for years before they reunite in DSSIII. They both clearly care each other greatly and their bond is considered more than just a familial or even a romantic one by Word of God.
This gets to the point, after years of ambiguous relationship that neither seemed to try to explain, that Word of God confirmed that yes, Roku and Kuronagi's relationship are romantic in nature and eventually explicitly shown in Reunion Fiction where they officially have a Relationship Upgrade into Official Couple status.