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.
Another possibility is that a new villain emerges as a result of the time - travel or whatever mechanism brings future Deku to the present. This villain could be from a future where Deku's actions (or inactions) have led to a more dangerous world, and he travels back in time to stop Deku from making those mistakes again. However, his methods are extreme and dangerous, making him the antagonist of the story.
Definitely The Flash. Their powers are quite different. The Flash's super - speed could be an amazing contrast to Deku's more physical - based quirk. Deku could learn about time - related concepts from The Flash, and they could have an interesting dynamic when it comes to chasing villains.
Toga could be an ally. Since she has her own complex relationship with the idea of heroes and villains, she might find Deku's transformation interesting. She could provide some of her unique skills, like shape - shifting, to help Deku in his villainous plans. Additionally, Twice might also join them because of his loyalty to Toga and his own sense of being an outcast in the hero world.
I think Uraraka would be very excited. She has always been a big supporter of Deku. Meeting Future Deku would give her a chance to see how far he has come, and she might also get some inspiration for her own hero journey. Plus, she's a friendly and emotional character, so she'd likely be thrilled at the opportunity.
Obviously, Deku is one of the main characters. Since it's a Saiyan Deku fanfiction, he is the one with Saiyan powers. Other characters from My Hero Academia like All Might or Bakugo can also be important characters in the story, as they interact with Deku in different ways because of his new Saiyan abilities.
He could be getting married to Ochaco Uraraka. They have a great friendship and there are many hints in the series that suggest a deeper connection between them. Their personalities complement each other well, with Deku's determination and Ochaco's cheerfulness.
In the 'deku texting story', Deku is the central figure. However, considering his world in My Hero Academia, other characters who could play major roles in the texting story are numerous. His friends from Class 1 - A would be prime candidates. They are constantly interacting with Deku in the original series, so it makes sense for them to be in the texting story. Additionally, any heroes or sidekicks that Deku looks up to or works with might also be main characters. Their wisdom and experience could be shared through texting, and they could offer guidance to Deku during his journey to become a great hero.
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.
The father of the world's novels generally referred to the European literary founder, De Vladimir Wolfe. Wolford is considered one of the founders of modern novels. His representative works include The Hunger Games, War and Peace, etc.
The father of the Chinese novel did not have a clear definition. Different scholars had different understandings of the definition and timing of the Chinese novel. However, it was generally believed that the origin of Chinese novels could be traced back to the long narrative poem "Song of Everlasting Sorrow" of the Tang Dynasty and the literary creations of the Song Dynasty such as Xin Qiji's "Sapphire Case·Yuanxi". In the Qing Dynasty, the creation of novels gradually became popular, such as Cao Xueqin's Dream of the Red Chamber and Lu Xun's Madman's Diary, which became an important milestone in the history of Chinese literature. Therefore, Cao Xueqin could be regarded as the father of Chinese novels.