I named myself after an RP character I never got to use. Valentyne is what I go by in real life as well as online, but they come from the same thing. When I was choosing a name for myself, I had several things in mind: I wanted it to have specific linquistic roots (French, it ended up being; all other feminine forms of the name are Valentina. It comes from the Latin "Valens" meaning strength), I wanted it to start with a "v" (I also considered Vivienne and Valerie), and I wanted a slightly unusual spelling (worked out because the "y" means people never pronounce the more common masculine form, which is "Valen-teen"). I looked over the characters I had written, and I came across one Valentine Lachance, who was planned for the third part of a roleplay that was currently on its second. I never used the character, but she was characterized by an unswerving goal, almost tunnel vision, to reach her homeland again, which she had been taken from as an infant. I liked this aspect of determination (as it someone reflects my own disposition) and the character herself was similar to me in other ways, and it fit all my other requirements (after changing the spelling), so I became Valentyne Lily Lachance, taking Lily as my middle name for personal reasons. (And maybe because I like flowers ┐('~`,)┌)
And that's the overly convoluted version of why my best friend calls me "Valley-girl" to my incessant annoyance.