Because of the "Gargoyles" show, back in the 90's. I created my own character, named Dublin. Kinda geek, I know. As for the Solo, it's linked to the fact that I had tho user accounts on my Xbox: "Dublin" for multiplayer, and "Dublin Solo" for the single player. Eventually, "Dublin Solo" won the battle, and it stuck to me.
As a matter of fact, my friends and my boyfriend call me "Dub".