Riddle Rosehearts/Relationships

MC
Both the MC and Riddle first encountered each other in the welcoming ceremony, when the MC was wrongfully sent to Twisted Wonderland, causing a ruckus during the ceremony and irritating the attendants, including Riddle, with Grim mistaken to be a companion / pet of MC. Riddle, alongside with Azul were the ones who has captured the rampaging Grim, and Riddle reprimanded the confused MC about bringing a pet into the school grounds, with such issue only clarified by Headmaster Crowley.

Later, the MC would encounter Riddle again, but they were dubbed a troublemaker by the latter. Riddle seems to belittle the MC for their incompetence and their inability to use magic, unaware of their origins. During the times of his tyranny, the MC and Riddle have gotten into a heavy dispute regards of how a leader should command and aid their members, with Riddle heavily controlling their activities, and the MC calling out Riddle of his ridiculousness, which heavily provokes Riddle. The MC's comeback is the final push to Riddle' overblot, causing a massive rampage within the dorm grounds. The MC, Ace, Deuce, Cater, and Trey have aided to take down and calm down the enraged Riddle.

After the overblot, Riddle apologizes to his dorm members and the MC for his recklessness and his irresponsibility, taking full account to his behavior and the consequences with it.

After the events of chapter 1, Riddle and MC would encounter each other at times, with Riddle occasionally reprimanding the latter, but overall their relationship has improved and can be considered good friends.

Ace Trappola
Both Ace and Riddle hail from the same hometown, and are in the same dorm together. Both Riddle and Ace' personality contrast' each other, oftentimes causing a dispute between the two. Such dispute is most evident during the events of Chapter 1 when Riddle has been overly controlling of the activities of his members, with Ace expressing his opinion of letting the members do as they desire. Such dispute had gotten to the point where Ace attempted to take Riddle's position as Dorm Leader in a challenge officiated by Headmaster Crowley, with the former defeated. During overblot, Ace, Deuce, Cater, Trey, and MC all defeated Riddle when he fully overblotted.

After the recovery from the overblot, Riddle apologises to his dorm member and MC, including Ace, who angrily demands Riddle to bake a cake for unbirthday party without Trey' aid as a way to express regret and apologise, which Riddle accepts as a form as punishment.

After the events of Chapter 1, both Riddle and Ace still work together, sometimes still getting into disputes, but their relationship overall has improved.

Deuce Spade
Riddle and Deuce are both from the Queendom of Roses.
 * Riddle acknowledges that Deuce, unlike Ace, is trying his utmost hardest to meet the standards of both the dorm and the college despite his not-so-stellar grades and equally bad troublemaking tendencies.
 * He offers Deuce his old math workbooks with annotations written into them.

Jack Howl

 * Sees Jack as a capable and upstanding underclassman, and is in turn greatly respected by the wolf beastman.
 * They're noted by Ace to have similar self-ideals and work ethic despite looking so different from each other.

Epel Felmier

 * Riddle sees Epel as a boy with potential and plentiful resolve to achieve his goals.

Sebek Zigvolt

 * In the Equestrian club together. Riddle recruited him during club day.
 * Although Sebek initially looked down on Riddle as a human (in typical Sebek fashion), he was quickly made to swallow his words when Riddle displayed his finesse in equestrianism. He now regards Riddle with great respect, but still tends to make blunt comments without realizing he has done so.
 * Riddle regarded Sebek as arrogant in their first interaction together, but saw that he was very diligent and cooperative towards those he respect and see as important.

Azul Ashengrotto

 * A fellow 2nd year dorm leader.
 * Riddle holds Azul's talent and capabilities in high regard, but does not trust him.
 * Azul, in turn, sees Riddle's abilities just as favorably. He once murmured to himself during the entrance ceremony that he wants to possess Riddle's Unique Magic for himself.
 * They've taken to tutoring Kalim together.

Jade Leech

 * Classmates (2-E). Riddle acknowledges that Jade is easier to deal with, but sees him as just much of, if not more, a threat as Floyd.

Floyd Leech

 * It's shown in the main and personal stories that Riddle does his best to avoid Floyd, mostly for his relentless teasing and general disrupting.
 * Floyd, on the other hand, thinks that poking Riddle around and seeing his face turn scarlet is the finest entertainment (that is, unless he's in one of his moods).

Kalim Al-Asim

 * A fellow 2nd year dorm leader.
 * Riddle and Azul often tutor him together.
 * As the scions of high-profile families, they seem to have similar sensibilities towards business situations. In the Scary Monsters! story, as the NRC students muse how to drive the Magicamonsters off campus, Riddle and Kalim are the ones to suggest talking it over a meal.

Jamil Viper
Jamil and Riddle seem to have an amicable enough relationship with each other. As seen in Riddle's PE Uniform personal story, the Heartslabyul dorm head even monitors Kalim when Jamil is not around, noting to the latter that "he deserves a break once in a while" from monitoring Kalim. Additionally, in Jamil's Labwear personal story, Riddle is hinted to be quite trusting of Jamil's abilities—even back when Jamil's true potential hadn't been revealed yet—and he isn't above giving the Scarabian a heads-up about an experiment he himself failed at, so long as Jamil (and Azul, who was with him at the time) get to show Professor Crewel that the second-years truly are of high caliber.

Silver
Riddle and Silver are in the Equestrian club together.

Trey Clover

 * The Heartslabyul vice dorm leader who often calms Riddle down when he's about to blow a fuse.
 * Riddle loves Trey's baked sweets.
 * Trey and Riddle are childhood friends from the same hometown and neighborhood. Trey, along with Chenya, would bring treats and invite Riddle to play during his solo study sessions when they were young.
 * When Riddle was caught out by his mother, however, Trey and Chenya became forbidden from approaching the Rosehearts residence. During the winter holiday, Trey states that they're still not allowed to visit Riddle at his home.

Cater Diamond

 * Despite Cater's socialite personality being the polar opposite of his, Riddle never seems to get truly angry at him.

Leona Kingscholar

 * Calls Riddle "the red young master" as a jab at his sheltered life.

Idia Shroud

 * Idia cowers in front of Riddle when they talk face to face (or rather, face to tablet), but behind the mic, he one day wants to pull a fast one on him to get back for the "nagging."
 * Riddle doesn't really hold animosity towards Idia, and just wants him to apply himself more as a dorm leader than can lead his students with confidence.

Malleus Draconia

 * The two respect each other as capable leaders who take initiative towards managing the members of their respective dorms.
 * Malleus admires Riddle's sense of responsibility, especially for someone he views as barely older than a baby. He offers Riddle guidance and support during the latter's Ghost Marriage personal story.
 * Riddle, in turn, looks up to Malleus as a senior in grade, magic, and nobility.

Divus Crewel

 * Riddle and Crewel are both from the Queendom of Roses.

Ashton Vargas

 * Riddle sees him as too hot-blooded, and doesn't appreciate that he prioritizes muscles over all else.

Alchemi Alchemevich Pinka (Chenya)
Riddle and Chenya are childhood friends. Along with Trey, they grew up in the same neighborhood.