Well, I'd say there are a few of me.
1. Inquisitive me - I ask lots of questions and carefully explore an idea someone else is talking about, while possibly expressing my own thoughts on it, and my own ideas that seem connected to it. I'm usually in this mode when I'm interested in and curious about something. This is probably the only mode I truly enjoy.
2. Formal me - I go mostly silent, and disappear underneath a series of stock phrases, commonly held perspectives, careful focus on work, and rigid behaviors to avoid seeming unusual or out of place. I can tolerate it, but it's not comfortable or rewarding.
3. Concerned me - I concern myself with someone else's happiness/comfort, and keep trying to do things that will make them feel better, subtly or openly depending on the situation. I try to offer compassionate advice, listen to them, say what they probably want/need to hear, etc. This can be rewarding and comforting in the long run, but it really isn't fun. It doesn't tire me at all, though.
4. Legalistic/Geek me - I pay careful attention to every detail, saying everything with precision and nitpicking at every flaw I see. Will complain about lack of precision and vagueness, decry unwritten rules and dismiss context and personal experience/values as meaningless things that create bias in perception. This can be fun when it's used on and off with 1. If it's used straight for a while, it's just tiring/tedious, though. Not really bad.
5. Irrational me - I moan and groan about every little thing that bugs me (noises, smells, pains, thoughts, fears, movements, etc), angrily tell people to shut up whenever they try to talk to me, and feel paranoid about everything I think to be paranoid about. I blame everything on other people, accuse them of ridiculous things, and won't take any responsibility for my own feelings. I also criticize everything other people do, sometimes with reason, sometimes arbitrarily. Sometimes I cry, sometimes I lash out violently, sometimes I yell, and sometimes I just lie down and refuse to move. There are certain people who can bring me out of this mode instead of waiting for me to get out myself, but they're rare. I don't like to be this way.
Those are the basics.