My worst RP partner.. Gee, that's a toughie. (I'm ashamed to say it, but) I started RolePlaying on a MineCraft server. There was honestly a good few decent RolePlayers and such (one of those being my mentor, who'd gotten me to the point where I had enough skill and vocabulary to write properly...
I don know if this has been said already, but what I believe makes an good antagonist is someone that has a sort of history with the protagonist. Whether it be directly, or not.
Speaking of history, the antagonist doesn't always have to have malicious motivations. In fact, a good antagonist...