Character introduction writers block hELhP

I've written the first few paragraph's of my friend's story. Basically, four boys awaken in an unknown place. It has a modernesque-purgatory-lobby feel; the ceiling is far up but the walls are narrow. It is quite bright but it's hard to pinpoint the light-source's location.

So these boys are all confused and afraid, right? Suddenly, they meet an old man who tells them they're in a training facility for people with supernatural abilities, and he's the teacher. No one has ever seen this man before. I'm already stuck on this man's introduction. How should he enter the room without filling the air with… pedophilic vibes? He's supposed to be a very central and beloved character to the story, so I don't want to give the impression that he has got some secret agenda for the teens. Any pointers on what I should do to lighten the mood?

@Beezer if you want to lighten the mood maybe make his entrance comedic? He could trip or something? Or fall down to them from really far up and mumble "well that wasn't supposed to happen." as he picks himself up off the floor? Maybe he could start introducing himself with something ludicrous and completely unrelated like "hello my name is Samantha I'm calling from the national diabetes association would you like to make a donation today?" or some other random charity or company and then mutter "no, that's the wrong one," and fly through some notecards he pulls out of his pocket.

I don't know if this is the kind of feel you're going for with your character but I hope it helps or at least gives you some ideas of your own. :)

I think that trust is earned, and an initial comedic entrance might help, but may make this trainer dude more of a comic relief character than you might want. If it feels natural for the boys to initially distrust this man, maybe they should, but over time his actions prove start that he's a good person. Character's aren't always likeable in the first scene, don't be afraid to develop his character over time.