Obviously, Tiny Tony Stark is the main character. But often, other characters from the Iron Man and Avengers universe also appear. Pepper Potts might be there, trying to help Tiny Tony or just being concerned about his new state. Sometimes, Rhodey also shows up, being Tony's friend and all.
In some fanfictions, there could be new characters created specifically for the story that interact with Harry and Tony. These characters might be hybrids of the two universes, having both magical and technological abilities. However, no matter how many other characters are added, Harry and Tony remain the central focus as they bring together the two very different worlds of Harry Potter and Iron Man.
Well, Nebula herself is likely to be one of the main characters interacting with him. They might have some interesting conversations about the technology they both use or their experiences in space.
One common character paired with him is Bruce Banner. They could be gaming buddies, with Bruce using his scientific knowledge to help Tony improve his games or vice versa. Another is Pepper Potts. She might be shown as someone who tries to get Tony to take a break from his intense gaming sessions.
There could be the foster parents. Maybe they are a kind - hearted couple who try their best to understand Tony despite his quirks. Another character could be a foster sibling who is initially jealous of Tony's intelligence but later becomes his friend.
Obviously, Tony Stark is the main character. But there could also be other characters like Pepper Potts, who might be his advisor or partner in ruling the world. Maybe Rhodey would also play an important role, helping Tony with military - related matters.
Often, you'll find characters who have a personal connection to Stark. Maybe a former employee of Stark Industries who has a deep sense of loyalty and joins the protection squad. Another could be a superhero friend of Stark's who decides to help out with the protection efforts. There might also be a character who was saved by Stark in the past and is now determined to return the favor by being part of the squad.
Most likely, Tony Stark himself is a main character as the story seems to revolve around him fainting while being sick. Pepper Potts would probably be another important character as she is often by Tony's side in these situations. And the other Avengers like Steve Rogers, Natasha Romanoff, etc. could also be involved as they are his friends and teammates.
The obvious main characters are usually the members of House Stark. This includes characters like Jon Snow, who might play a crucial role in leading the house to prosperity. His unique background and skills could be a key factor.
One common character paired with him could be Pepper Potts. Their relationship could be explored in a new light with Tony having psionic powers. Maybe Pepper has to deal with a more powerful and sometimes unpredictable Tony.
His parents, Howard and Maria Stark, are very common. They play important roles in shaping Tony's childhood. Jarvis, the family butler, also often appears. He could be the one to encourage Tony's scientific pursuits or keep him out of too much trouble.