Well, Peeves is actually one of the good ghosts, too. He's just a little bugger. He mostly just pulls harmless little pranks. One of his favorite things to do was throw water balloons at the first-years. He can be a little overbearing if you have the chance to meet him, and he occasionally speaks in rhymes.
None of our ghosts will try to possess you, so you're fine. The only thing that would make you seem 'possessed' is if someone put you under the Imperius Curse, which is forbidden in our world and unforgivable. People have been forced to do terrible things under the Imperius Curse. The other two unforgivable curses are the Cruciatus Curse and the Killing Curse.