Overview
Thomas is the main protagonist of Somnium, and Me's neighbour.
Appearance
Thomas has long, brown hair that seems to be dirty and messy, along with a red shirt with indigo overalls. Although he is a boy, a lot of people tend to mistake him for a girl due to his hair. Another thing to note is his Earthbound-like eyes, which may be a consequence of the art style. He walks barefoot, and seems to be very thin for some reason.
In a daydream, you can change his pallete to the colors of the various Yume Nikki fangame characters, including even Madotsuki herself.
In his sprite, his eyes are open, but they close from time to time while he is walking around.
Personality
Thomas is seemingly a quiet person, with possible emotional issues, due to the whole nature of the game. While he doesn't have effects per se, sometimes, in the daydream, he changes the sprite or just changes completely, which probably shows sides of him.
In the official ask blog, he seems to change between a jerk, a confused boy and an insecure person.
It is highly probable, however, that he might be a fan of a certain series...
Past
Not much is known about Thomas, though the myriads of daydreams may show either his view on things, places, or people, or show how he feels about something.
The only few things that are known from Thomas is that he has/had a family (The NES at his room mentions his father) and that he and Me were friends until they had a fall-out recently, reasons being disclosed. Me is also frequently shown at the daydreams, either as small references, or even she appearing.