He might start blushing more often and be unable to look the person he loves in the eye without getting flustered. Izuku could also become more clumsy around them, tripping over his own feet or dropping things.
The Gamer Quirk also changes Izuku's relationship with others. He can now offer unique insights based on his quirk. For instance, he might be able to analyze a villain's attack pattern like it was a boss fight in a game. His friends and allies can then use this information to their advantage. This makes him a valuable member of any team. At the same time, it also means that he might be seen as a bit of an oddball because his thinking is so different from the norm. But overall, it helps him form deeper connections with those who understand and appreciate his quirk.
In fanfiction, if Izuku was hit by a love quirk, he might start acting in a very affectionate way towards a particular character. For example, he could become overly protective or constantly seek the person's attention. His normal shy and reserved self might be replaced with a more forward and love - stricken version.
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His relationships with his friends would likely become more complex. If he starts using his time quirk to change things, his friends might not remember the original timeline, but Izuku would. This could create a sense of isolation for him as he holds memories that no one else does.
An ancient quirk can also make Izuku more in - touch with history. If his quirk has roots in the past, he might study old hero tales and cultures more, which broadens his perspective. He becomes more of a knowledge - seeker as well as a hero - in - training. He may also develop a sense of mystery around him as his ancient quirk sets him apart from his peers.
His relationship with Bakugo might change. Bakugo, who used to look down on Izuku, might now be a bit jealous or even more competitive as Izuku's Dragon Slayer quirk is very powerful. With his friends like Uraraka, she could be in awe of his new quirk and support him more actively in battles. Izuku might also attract the attention of some of the more powerful heroes in training, who want to team up with him because of his unique ability.
His relationship with his teachers could also change. The teachers might be more interested in studying his sentient quirk, which could lead to special training or extra attention. This could either make Izuku feel special or pressured, depending on how the author writes it.
Some characters might be immediately terrified. They could avoid Izuku or even try to drive him away. For example, classmates who don't understand his quirk might spread rumors about him.
In some fanfictions, because of his powerful quirk, Izuku becomes a sort of mentor figure to his classmates. For example, with his enhanced understanding of his quirk in these stories, he can help his friends train and develop their own quirks better. So his relationship with them shifts from being just a peer to a more guiding one.
His relationship with his mother could become more complex. She might be worried about his new nature and try to protect him more. With his friends, like Bakugo, they might initially be scared or distrustful when they find out about his quirk.