Ha nice thread!
One of my worst character traits is that I am an obsessive control freak - one of my best friends now hated my guts for about 3 years before we became friends. We used to be lab partners in science lessons, and I would never let her do anything in case she got it wrong or something... I was such a bitch to her!
I'm also ridiculously insecure about anything and everything, regardless of how irrelevant it may be