In my case -- I'd been a member of another LGBTQ-aligned fleet since around STO's launch. Nice group of people, but I never really felt like I fit in. I couldn't really say why, but we just didn't click.
So I kept looking. I suspect at some point I saw a ship flying around with the Stonewall flag on it, and did some Googling. In July of 2015, I finally got around to applying to the fleet.
It's significant that I joined in July, because the summer event was going on, and my first face-to-face meeting (in-game) with any of my fellow fleeties was on Risa. At that point I knew I wanted to stay, 'cuz as you know, Stonewall members are smokin' hot. As time passed, I also found they were really fun people to hang out with.
Most important, though, is I feel like I fit in Stonewall Fleet. I have never felt like an outsider from the day I first joined, and I'm very familiar with feeling like an outsider. Don't let my stunning good looks and brilliant wit fool you -- I am a socially awkward penguin of the highest degree, and to feel like I belong is pretty huge to me.
Stonewall doesn't just say they're welcoming and inclusive as a marketing line -- we really are. See, I said "we." Rolled off the keyboard totally naturally, like I feel like I belong or something.
Anyway, that's why I'm here.