Funny story that I used to be afraid of talking about, actually.
Around late 2014, I somehow ended up a fan of the kids show My Little Pony: Friendship is Magic through the fan-made Ace Attorney case Turnabout Storm. At the time, the handle I used still included my irl name, and I didn’t want to use it for anything related to MLP as I was… “ashamed” of it. After watching the movies and finally catching up on the fanfiction site, I instantly fell in love with the SunLight ship, which is Sunset Shimmer and Twilight Sparkle. As a 15 year old kid, I wasn’t very creative, so I mixed the two names up and became Sunset_Sparkles. No, I don’t know why I added the extra “s” at the end. Eventually met Twilight_Shimmer. We talked. Cool guy.
Then after a year or so I joined a MLP Minecraft server. My Minecraft username was still my old handle, but at that point I wasn’t as ashamed, and that specific server had a nicknaming system. Since Sunset_Sparkles was too long, I shortened it to SSparkle. Subsequently, I created a new email account, as I always do when I decide on a new handle. ssparkle was already taken, unfortunately, but Google usually adds numbers as suggestions, and the first suggestion was ssparkle31. Being lazy, I just picked it. 31 also reminds me of pi, which is my favorite number because I’m a math nerd. 0314 is also my Discord tag, and I was born at 03:14 AM. Go figure.
Fast forward a few months, I started getting into anime. By that point, multiple users had mistook me for a girl due to how “feminine” the nickname sounded (their words, not mine), so I decided it was time for a change. However, I had grown fond of it and didn’t quite want to part with SSparkle31. At that point I was already 16, and thought “You know what’s cool and manly? Sparks”. I hadn’t grown up a bit. Still haven’t. This is fine. That marked my MyAnimeList account, SSparks31, as the first using my current handle. As per usual, I have many variants in case someone else already used SSparks31 (or if I lost an account and have to make a new one). These include SSpark31, SSparks, and SSpark. Like I said, creative. It didn’t really solve the issue it was supposed to, but I stopped caring. Eventually I created a Reddit account, and from there it just stuck. And it will, until I’m ashamed of liking visual novels and want to distane myself from the handle I used to talk about them. Probably never, but who knows.
tl;dr without all the tangents: I like MLP and my favorite ship is Sunset Shimmer and Twilight Sparkle, had to shorten the former because the whole thing was too long, Sparkle made people think I was a girl so I changed it to Sparks, 31 is just a random number Google gave me