For Deku's relationship with All Might, All Might would need to guide him in a different way. Since the dragon quirk is so different from One For All. His classmates might start to rely on him more in dangerous situations because of the power of his dragon quirk. Some might be jealous, while others would be excited to train with him and learn from his new abilities.
His relationship with Bakugo would be very different. Instead of Bakugo looking down on Izuku for being quirkless, he might be jealous of Izuku's powerful fire quirk. This could lead to even more intense rivalries between them. With All Might, All Might might be more cautious in training Izuku as a fire quirk could be more dangerous to handle without proper control.
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 mother would be extremely strained. She might be in denial about her son becoming a villain and try desperately to bring him back to the light. With his former friends like Bakugo, it would turn into a bitter rivalry. Bakugo, who used to bully him, now has to face a much more dangerous and calculating Deku.
If Naruto had a powerful quirk, his relationship with Sasuke might be more competitive. Sasuke is always striving to be stronger, and if Naruto suddenly had an extremely powerful quirk, Sasuke would be even more determined to catch up or surpass him.
His relationship with Sasuke could become more complex. Sasuke might be both envious of Naruto's new power and also worried about Naruto losing his humanity in the dragon form. Sakura could be initially scared but then determined to help Naruto control his form, which would strengthen their friendship. His relationship with Kakashi would change as Kakashi would now have to mentor Naruto in a different way, guiding him to use his dragon powers for good and not let them consume him.
His relationship with All Might would also be affected. All Might might be more cautious about Izuku's quirk as it's very powerful and could potentially disrupt the fabric of time. Izuku, on the other hand, could use his quirk to go back and learn more about All Might's past, which could strengthen their bond as he gains a deeper understanding of his mentor. However, it could also create a rift if Izuku discovers something in the past that he doesn't like about All Might's actions.
With his classmates, some might be scared of Izuku. They've known him as a kind - hearted person, but the All for One quirk has such a dark reputation. However, some like Ochaco might try to understand him better and support him through his journey with this new quirk. His relationship with the teachers would also be under scrutiny. They would need to ensure that Izuku doesn't use the quirk for evil purposes, which could lead to a lot of extra monitoring and a sense of unease in their interactions.
His relationship with All Might would become extremely complicated. All Might, who passed on One For All, would be shocked and perhaps a bit disappointed that Izuku now has the All For One quirk. He might question his decision to choose Izuku as his successor. With Bakugo, their rivalry could take a different turn. Bakugo might be both envious and afraid of Izuku's new power, leading to more intense confrontations. And with his friends like Iida and Ochaco, they might be initially hesitant around Izuku, not knowing if he can still be trusted with such a villainous - associated quirk.
On the other hand, his Gamer Quirk can also bring him closer to some characters. If there are other characters who are also into gaming or understand the concept of leveling up, they might bond with Midoriya over it. For instance, he could form a closer friendship with a character who also has a quirk that has some game - like elements. They could exchange tips on how to better use their quirks.
His relationship with All Might could change. All Might might be both proud and a bit worried. Proud that Midoriya has this new power from his ancestry, but worried about how it will affect Midoriya's growth and the way he uses his existing quirk. They would have more in - depth discussions about power management.