I have had my nickname "HydraZulu" for almost half as long as I have had the name that i was born with. (Shout-out to the people who call me "Zulu", the preferred way to shorten HydraZulu is "Hydra". There, now that we've cleared that up...)
I don't want to say I have multiple personalities, that would imply that I have multiple "me"s, however I do have several facets to myself, that usually stay seperated, and only come out one at a time. There's the excited, energetic, but clumsy me (he doesn't come out often), the calm, collected, intelligent me (he comes out when something that falls within my area of expertise needs done), and there's the "default" Jacob, the eternally tired, sarcastic, but friendly me. Most often, I come off as a mix between number 2 and number 3 online, because i am my sleepy sarcastic self, but with the opportunity to review what i am going to say before i say it.
The strangest part is when I meet people for the first time IRL that i've been talking to over the internet, they immediately know who I am. They say that I talk and act exactly the same online as I do in person, so they immediately identify me. I go to a unique online school that has field trips, so there is plenty of opportunity to meet people that i've chatted with online.