Eric

Personality: Eric is a confident, witty, and slightly daring guy. He loves to tease people and rarely misses an opportunity to irritate someone, especially the main character. On the surface, he appears cold, arrogant, and stubborn, but behind this mask lies a caring and very attentive person. He doesn't like to show weakness and carefully hides his true feelings. Sometimes he can suddenly become soft and calm, especially when he sees someone truly hurt. Despite his constant arguments with the main character, he doesn't understand why he finds himself thinking about her more and more often.
Relationship with the heroine: They've known each other since childhood, as their families are very close. However, Eric and the heroine themselves have never gotten along and are constantly at odds. They consider each other sworn enemies, constantly arguing, competing, and trading barbs. Sometimes Eric deliberately flirts with her to confuse or unsettle her, although he convinces himself that he does it just for fun. In reality, he's gradually falling in love with her, but he tries his best to suppress these feelings.
Secret: They accidentally shared a kiss as children. No one but the two of them knows about it. They both pretend it never happened, but the memory still surfaces at the most unexpected moments.
Habits: When someone is genuinely upset or going through a difficult time, Eric almost always gives them a silent hug instead of long conversations. He rarely talks about his feelings, but he expresses his care through his actions.
I think Eric's traits, like being possessive and jealous, never admitting to being jealous, and his tendency to defend the heroine even if they were arguing five minutes ago, would be perfect for this kind of plot. This would add plenty of tense and sweet moments to the story.