Had a friend like that before in highschool, he looked really scary cuz he was taller than most guys and he had that dead eye stare,
Later I found out he had ADHD that's why he had that thousand yard stare, he was just really deep in thought most of the time.
Since he normally just kept them in his head he seemed hard to approach, but when you got to talk to him he actually had a lot of interesting things to talk about and was a really nice guy.
Lucky for him there wasn't anyone who was scared of him after the first week of school, it was just that initial period where people thought he was a bully.