Well, Izuku's sentient quirk could make his training more challenging in some ways. Since the quirk has its own thoughts, it might not always agree with Izuku's training methods. There could be clashes between what Izuku wants to do and what the quirk thinks is best. This would force Izuku to find a compromise and develop new strategies for training that satisfy both him and his quirk.
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.
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.
His training would likely start with basic control. He'd practice making small objects move up and down with different levels of gravity. For example, he might start with a pencil, trying to make it hover gently or drop quickly. Then he'd move on to larger objects like weights in the gym. He'd also do exercises to improve his reaction time when using the quirk, so he can quickly adjust the gravity in a fight.
Well, with a green fire quirk, Izuku would likely have to train in environments that can withstand fire. This means his training grounds would be more specialized. He might also need to study the chemical composition of his green fire to understand its properties better. For example, if it has some sort of special element in it that can be used against certain types of enemies. Training would also involve learning how to use the fire in different forms, like a thin stream for precision attacks or a large blast for taking on groups of foes. And he'd probably have to work on his endurance, as using the fire quirk might drain his energy quickly.
In fanfiction, Izuku's pride quirk could make his relationships more complex. If his quirk is related to personal pride, he might be more self - focused at times, which could cause some friction with his friends. For example, he might be so determined to prove his pride in his quirk that he doesn't listen to their advice.
A sentient quirk for Izuku in fanfiction could have a huge impact on the plot. It could be a source of both power and trouble. For instance, villains might try to target the quirk specifically, seeing it as a valuable asset or a threat. Izuku would have to constantly protect it while also using it to his advantage. The quirk could also communicate with other sentient entities in the fanfiction world, opening up new storylines and alliances.
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.
Some fanfictions explore the idea of Izuku's sentient quirk being a bit mischievous. It could play pranks on him or get him into awkward situations, while still being a powerful asset in the hero world.
When Izuku has a mythical quirk in fanfiction, say a power to transform into mythical creatures, it can change how others perceive him. His classmates might be in awe or a bit scared at first. But as time goes on, they would learn to work with his new abilities. His relationship with his teachers also changes as they have to figure out how to train him to control this unique quirk.
In a fanfiction where Izuku's system quirk is very powerful, it could lead to some characters feeling inferior. However, his closer friends like Ochaco or Iida might see it as an opportunity for all of them to grow. They could train with Izuku to better understand his quirk and improve their own skills. On the other hand, villains would likely target him more, which could put a strain on his relationships as he tries to protect those around him from the danger his quirk attracts.