Should you write a prologue? I don’t know – it’s your story. I can tell you what I think and if that helps, hey – I’m chuffed. But I’ll tell you two things up front – one, I don’t usually like prologues and two, I’ve written one myself.
Characterisation is at the heart of any really good story as far as I’m concerned. Real people dealing with real situations. Or sometimes (as in speculative fiction) not-real situations. That’s when creating believable characters becomes absolutely crucial. If your characters aren’t believable, your reader won’t relate to them.