In most of such fanfictions, they might create evidence like hidden past connections. For example, AFO could be secretly involved in Izuku Midoriya's (Deku) family history. Maybe he had a relationship with Deku's mother long ago, which led to Deku's birth. But it's all fictional speculation within the fanfiction world.
One common plot twist is that Deku discovers the truth about his father in a moment of great crisis. For example, when he's facing off against AFO in a big battle, AFO reveals the truth to him, which completely shakes Deku's world view.
Millions and AFO were both important characters in My Hero Academy. They both had great strength and abilities. However, who was stronger depended on character settings and battle strategy.
Million Passers was one of the strongest heroes in My Hero Academy. He had invincible walls and unparalleled strength. His ability can resist all attacks and can reflect enemy attacks through walls. In battle, he usually adopted a static defense strategy to defend against the enemy's attacks by holding his position. Thus, the static defense of a million was very strong.
AFO was another very powerful character in My Hero Academy. He had the ability to fly and teleport. His ability allowed him to teleport anywhere and attack the enemy's weakness. In battle, he usually used dynamic attack strategies to defeat the enemy by moving quickly and attacking. Therefore, AFO was very powerful in terms of dynamic attacks.
Both Million Passers and AFO were very powerful characters. The stronger one was, the more determined the character's combat strategy and settings. Under certain circumstances, the Million Passers may adopt a more static defensive strategy, while under certain circumstances, AFO may adopt a more dynamic offensive strategy.
The main differences are in their expressions and some minor details of personality. In the manga, Deku might seem a bit more intense, while in the anime, he's sometimes presented a bit softer.
Deku might be completely shocked at first. Since Bakugou has always been so aggressive towards him, he would never expect such a confession. He might just stand there, mouth agape, not knowing what to say.
His friends could come to the rescue. Bakugo, for instance, might use his explosive power to break into Toga's hideout. He's always been competitive with Deku, but he also cares about him deeply.
In 'deku meets future deku fanfiction', perhaps the future Deku warns the present one about upcoming threats. He could tell him about villains he'll face in the future and how to defeat them. This would give the present Deku an edge in his battles and also in his growth as a hero.
Well, obviously Deku in two forms - the younger and the older version are the main characters. The younger Deku is the one who is still growing and learning, while the older Deku has more experience.
As of now, Deku is very much alive in the manga. The plot hasn't reached a point where he meets such a fate. Usually, main characters like Deku have significant story arcs and aren't easily killed off.