Mine's strangely uncomplicated, but anyway:
I was playing a game called 1602 A.D. one day, and had to order another ship built as the AI had just destroyed one. When the game adds a new ship to your fleet, it gives it a random name from a list; this one came out with the name Drake, which can be associated with a type of duck and dragons.
I had been searching for a new name to use on the collective internet and in games by this point, so after considering the dragon angle, Drake stuck. But I wasn't done there.
Knowing Drake by itself was going to be a common name around the net, I decided on a Firstname Lastname angle. My neighbor had been on an Egyptian Gods kick at the time, so I went with Osiris. I'm STILL not certain exactly what he does, but I'd heard he was the god of the dead at one point and the name sounded cool. I thought this name was going to stick for the rest of my life, and for a while, it stuck like glue...
... Then I found Second Life around two and a half years ago. When you sign up, you have to use a Firstname Lastname combo: your first name is whatever you want, and you select your last name from a list that changes every so often as given names get old. You can actually get some catchy combos from this, but I wanted to retain at least part of my existing name.
Osiris, to my knowledge, still is not and never has been in this list, and I'd rather change my name than make it look stupid. (DrakeOsiris Beck?) While scrolling through the names, Spyker popped out and practically hit me like a ton of bricks. It was a change in flow from Osiris, but it still worked well, and I liked the look of it, so I kept it.
Now, it's taken a couple of years, but Drake Osiris gradually fell out of use. I don't use it anywhere anymore except for nostalgia, though both names have served me well: I haven't once encountered a conflict on any website I've used them with, and I doubt I ever will unless someone does it just to spite me.
I don't intend to ever change it again, either.