1. He plays mind games.
2. His job will forever cause suspicion. And you can't say anything because it's "art."
3. He parties pretty hardcore.
4. He's a total dreamer.
5. He's non-committal.
6. Jack is a user of "the neg."
7. He has an inflated ego.
8. He's too much of a risk-taker.
9. Getting Jack to quit smoking would put you through hell.
10. He'll always win you over with charm.
One minute you're in a fight with him about all the things, the next, dude is kissing your hand and making you all melty, thereby circumventing the whole conflict. And leaving all the things unresolved.