I don't know much from the comics so this is all coming from the movies, don't bight my head off if I'm wrong in some areas. This is not a self-insert or a Mary-Sue (don't know the male term for that). Just doing this so it gets out of my damn head.
Carl Stark:
Original last name is Van Tol
Adopted son of Tony Stark after parents are murdered. Unknown killer
Adopted at age 12
20 years old
5'11"
Blonde Hair
Blue eyes
Very pale skin
Chubby
Has many scars
Average intelligence
Nerd
Sometimes words don't come out right
No real special skills besides messing with Jarvis and getting into Tony's files
No powers
Just wants to get on with his life
Does not like Pepper, but when she escorts all of Tony's special lady friends he laughs at what she says to them
He loves Tony like a father but refuses to admit it
Kind of had Tony's attitude, not as arrogant, lets his thoughts slip out accidentally
Likes to screw with Jarvis, and Pepper
Tony Stark "Iron Man":
Same appearance as the movies and attitude
Protective of Carl, some would say overprotective
Feels responsible for Carl's parent's deaths, but won't explain why
Constantly trying to get Carl to stop being nasty to Pepper
Tried to teach Carl important skills, including business, fixing cars, and other such things
Pepper:
Same appearance and attitude in movies
Dislikes Carl just as much if not more than he does for her
Has been driven to a panic constantly by Carl, and Tony both
Obadiah:
Same as movies
Director Fury:
Same as movies
Has an interest in Carl for some reason
Bruce Banner "The Hulk":
The Edward Norton Hulk but it looks like Ruffalos human form
Might be the reason why Carl's parents are dead
Clint Barton "Hawkeye":
Same as in movies
Calls Carl by his original last name
Like an older brother to Carl
Eventually starts giving Carl fitness training
Natasha Romanoff "Black Widow":
Same as in the movies
Hair from Iron Man 2
Helps Clint with the training
Steve Rogers "Captain America":
Same as in the movies
Not as idiotic about future tech
Is effected more with the PTSD
Thor Odinson:
Same as in the movies
With Sif, instead of Jane Dawson
Loki:
Same as in the movies
Phil Colsin:
Same as in the movies
More awkward around Carl than anyone else
Maria Hill:
Same as in the movies
Doesn't give much attention to Carl
Wanda Maximoff "Scarlet Witch":
Same as in the movies
Shares a connection with Carl due to them being the only ones alive in their families
Pietro Maximoff "Quicksilver":
Same as in the movies
He hates Carl while he is alive