Stephen

Stephen is the main character of the Horror Magic School bus. He's a curious kid in the 6th grade who is an only child living with his Father. He ended up in Ms. Frizzle's homeroom class, and while he starts the series as a normal student, he eventually becomes one of Ms. Frizzle's favorites and is now trapped in the loop.

Personality
At the beginning of the series, Stephen is absolutely terrified of his time in Ms. Frizzle's class. As the show progresses and he spends more time in the class he slowly loses his terror and curiosity takes over. Stephen is always asking questions: Why are we here? Why is this happening? Who is Ms. Frizzle? What is Ms. Frizzle? Originally these questions were panicked and terrified, it was hard to tell if he truly wanted the answer or if he was simply trying to make sense of the chaos going on around him; however, soon these questions became genuine. As he became more comfortable with his new reality he started theorizing, quizzing the other favorites, and trying to unravel the mystery of the Frizz.

Stephen is pretty good-natured. He has an average temper and his frustration is usually caused by exasperation when he isn't receiving answers or isn't being taken seriously. He sometimes carries a dead-panned tone when he is completely overwhelmed.

Physical Description
Stephen, like all the characters is played by cleric_34. He is depicted as wearing a pink baseball cap, glasses, and a t-shirt under an orange and black flannel shirt. His t-shirt changes color but the color of the flannel usually stays the same. Sometimes he is depicted wearing a black backpack and carrying around a pen and notepad.

Stephen has gone through a couple looks, at first he was mostly seen in various shirts and without glasses. The pink baseball cap makes its first appearance in Episode 6 of season 1, while his glasses don't become a part of his outfit until episode 19. Stephen eventually seems to settle into a consistent outfit in the Troy Chronicles.

Stephen's Dad
Stephen has an interesting relationship with his father. One moment his father doesn't believe a word he says about Ms. Frizzle and her field trips and in the next he is giving him cryptic information about the world of the Frizz. Stephen's dad cares about his son even if the loop interferes with his memory. He always tries to relate to Stephen and asks him about his day almost every time he returns home from school. He clearly wants to help his son, but isn't in a position to.

Ms. Frizzle
Stephen's homeroom teacher and the current source of all his misery. Stephen is both terrified and fascinated by Ms. Frizzle. While initially he just wants for her class to be over, he soon grows to want to know the truth about the Frizz herself. In turn, Ms. Frizzle seems equally interested in Stephen. His curious nature is one of the main reasons he becomes a favorite and while she hasn't exactly told the students how she chooses her favorites it's clear that something about Stephen has caught her attention. She has been seen talking to him alone multiple times and her interest has even attracted the jealousy of other favorites.

Carlos
Carlos is the first favorite that Stephen meets and becomes his sort of psuedo-guide to surviving Ms. Frizzle's class. He initially tries to stop Stephen from digging into Ms. Frizzle's goals and origin but stops when it becomes clear that Stephen has already dug too deep.

Troy
A new student that Stephen befriends. Troy seems equally as interested in figuring out what the Frizz is, but where Stephen's interest comes from a need to know, Troy simply wants to use it to escape the loop. Troy wraps Stephen up in his scheme to get rid of Ms. Frizzle, but Stephen ultimately tries to talk him out of the plan.

Trivia

 * Stephen is the only character known to be LGBT+. The creator confirmed Stephen to be bisexual in a comment.