Paranoid is always suspecting it will go wrong. He is paranoid that the traffic will always be bad, and that many drivers will be rude and cut him off on the road.
Obsession can be about facts that are true and always thinking about this one thing. Obsession can dominate over other thoughts and may cause a disconnection from reality of other things. It can be a positive obsession.
He is obsessed with watching the television program. He loves it. He has t-shirts with the characters' names on it, posters in his room, and even a video game.