Sero's sister

⚠️Info about YN's past⚠️

Y/N grew up in a supportive household alongside her older brother, Hanta. Their family was always encouraging, but the weight of having a brother in the hero course meant there were unspoken expectations for her to follow in his footsteps. Though she adored Hanta and admired his easy-going personality, she was determined to carve out her own path, free from being "Sero's sister."

From a young age, Y/N discovered her quirk, "Shockwave." It was powerful but difficult to control at first, and she had to put in years of hard work to refine it.

When she was around 13, not long before entering U.A. High, Y/N met someone who would change her perception of relationships. His name was Kaito, a boy from her middle school class with a strong quirk, charisma, and an initial charm that captivated her. At first, Kaito seemed perfect—attentive, sweet, and encouraging. He admired her strength and independence, which Y/N mistook for genuine admiration. But as the months passed, his true nature started to emerge.

Kaito had his own issues, particularly an obsession with control and power. He loved how strong Y/N was, but only as long as her strength didn't overshadow his. Gradually, he became possessive, undermining her confidence in subtle ways, telling her things like, "You're strong, but you need to rely on me more. I can help you be better."

It wasn't long before Kaito's behavior turned manipulative.

He started criticizing Y/N's quirk saying that she wasn't using it to its full potential, or that she was reckless and needed him to show her the "right" way to fight. At first, Y/N took his words to heart, thinking that maybe he just wanted to help her grow. But as time went on, his comments became more demeaning.

"You're too emotional in battle," 

"That's why you always lose control."

He chipped away at her self-esteem bit by bit, isolating her from her friends and making her feel like she wasn't enough on her own.

It was a cycle of manipulation—he would push her down, then offer to help her get back up, pretending he was her only lifeline.

Y/N didn't see it for what it was at first. She thought she was lucky to have someone who cared so much about her growth. But Kaito was toxic, using her insecurities to control her, and Y/N, still young and in love, struggled to see it.

It wasn't until Kaito's possessiveness escalated that Y/N realized how damaging the relationship had become. He began to criticize her for spending time with others, especially her brother Hanta, calling it a "waste" of time.

Instead of helping her regain control, Kaito yelled at her, calling her "dangerous" and "unpredictable." His words cut deep, making Y/N doubt her ability to control her quirk. For the first time, she truly saw how toxic he was, how he enjoyed making her feel small and inadequate so that he could feel superior.

Shaken and emotionally drained, Y/N finally found the courage to end the relationship. She cut ties with Kaito, even though it hurt, and vowed to never let anyone undermine her strength again.

By the time she entered U.A., Y/N was more guarded than before. She had rebuilt her confidence, but the scars from her toxic relationship remained. She was determined to focus on becoming a hero and proving her worth on her own terms, without relying on anyone else.

Though Hanta knew something had happened between Y/N and Kaito, she never gave him the full story. She didn't want to be seen as vulnerable or broken, so she kept the details to herself, burying the pain deep down. Her brother could sense that she was more serious and driven than before, but he never pressed her for the truth, respecting her space.However, her experience with Kaito left her wary of relationships, especially with strong personalities like Bakugou's.

However, her experience with Kaito left her wary of relationships, especially with strong personalities like Bakugou's.

She wasn't about to let herself get involved with someone who could end up controlling or belittling her again, which is why she often pushes back so fiercely against Bakugou's fiery demeanor.

Impact of the Toxic Relationship on Y/N's Present:

Trust Issues: Y/N is cautious when it comes to letting people into her life, especially romantically. She's built walls around her heart, fearing that if she lets anyone get too close, they'll end up controlling her like Kaito did.This is why she often appears distant or uninterested when people flirt with her or show her attention.

Determined to Prove Herself: The relationship with Kaito left Y/N with a deep need to prove her strength and independence. She pushes herself harder than most, always striving to be better, to show that she doesn't need anyone else's approval to be strong. She's meticulous about controlling her quirk, terrified of ever losing control again like she did during that final fight with Kaito.

Her Dynamic with Bakugou: Initially, Bakugou's aggressive and confrontational nature rubs Y/N the wrong way, reminding her too much of Kaito's need for control and dominance. She bristles whenever he challenges her, and she fights hard to maintain her independence around him. The tension between them is undeniable, but Y/N is hesitant to let her guard down. She's attracted to Bakugou's raw power and intensity, but she fears getting too close, worried that history will repeat itself.

Conclusion:

Y/N's backstory with Kaito adds layers to her character, explaining her fierce independence and reluctance to trust others. It also creates a compelling dynamic with Bakugou, as he challenges her in ways that both excite and terrify her. Their relationship, while filled with tension, could ultimately help Y/N heal from her past, showing her that strength doesn't mean pushing people away—but rather standing firm in who you are, with or without someone by your side.