Riddle Rosehearts/Relationships

Ace Trappola

 * From the same hometown, the Country of Roses.
 * As a student of dorm he leads, Riddle regards Ace as a troublemaker who tries to get the easy way out of work, but he knows he'd have potential if he just applied himself.
 * In the Ghost Marriage event story, Riddle is shown to have gotten accustomed to maneuvering Ace into a desired action, like when he pits him up against Epel to stoke his competitive spirit.

Deuce Spade

 * From the same hometown.
 * 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.
 * 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 episode 2-11 and side stories that Riddle does his best to avoid Floyd, mostly for his relentless teasing.

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.

Silver

 * 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 Che'nya, 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 Che'nya 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

 * From the same hometown.

Ashton Vargas

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

Alchemi Alchemevich Pinka (Che'nya)

 * Riddle's childhood friend from the same hometown and neighborhood.