I think mine was Experiment 505.

I think the first Sue I read was the one that I eventually took on as a first mission. When I read a Card Captor Sakura fic, I expect to be, well, about the original cast. Not about a OC who's having a love story with another OC, and the canon characters only in supporting roles with almost no mentions of the original plot.

However, I actually think I might have written my first Stu before I stumbled on that one, so... *points at Agent!Sergio* That would be him.

I can't think of the first Suefic I read, which probably means I blocked it out.

I once wrote a Harry Potter fanfic about a princess called Acacia (ha ha) who was a Wood Elf and romanced Ron Weasley. It was a weird fic and just made no sense, and everyone kept calling Acacia a Mary Sue while I defended my "wonderful" OC.

Then, there was my Edelweiss Flower series...we don't speak of that anymore.

A friend of mine once wrote a Harry Potter/Lord of the Rings crossover about a girl whose dad was a wizard and whose mom was a High Elf. We now laugh about that fic.

Sorry for giving my Mary Sue the same name as one of your beloved founders.

I'd have to say mine was the Naruto from One Man Team. Replacement Sue for sure. He was smart, ruthless, and had quite the tragic backstory. All of it was non-canon, of course. The issue wasn't with that alone, though. Everything was distorted around him, with only about four characters not being derailed by the end. Kakashi, the hokage, Hinata, and Gaara. Everyone else was either distorted massively, especially Sasuke and Sakura, or was given too little screentime to be distorted.

It's a shame, too. the author had plenty of talent, and the story was well written. But everything had changed for the dark and edgy sue, and it eventually ruined it for me.

This one, if you're curious. A friendly person on the message board I lived on at the time asked if I thought my OC might be a bit of a Sue. I was like, "Huh? What's that?" I don't remember exactly how they explained it anymore, but it was something like "a character with idealized traits of the author," and my response was pretty much "Oh. Then, yes, you could certainly say that!" It took me a while to figure out the more negative connotations. It was probably OFUM that really gave me a solid idea of why Sues are not good, and from there the PPC.

To this day I don't think Jen'ra is awful, though. The story's kinda wooden and awkward and predictable—oh, and the chapter with her backstory is particularly cringy—but I've never seen a clear angle to mission it, myself. *shrug* If anybody else wants to, though, you have my permission. I seem to have a problem with green-eyed female OCs, so one less in the stable would not be a bad thing. Plus, Jen'ra is literally an alien expy of Jenni, so she's expendable. ^_~

~Neshomeh

I'd just finished the second-to-last Sisters Grimm book and went wandering around the internet trying to find out if the last had been published already or not... and that was when I first stumbled across fanfiction. Someone had written an entire novel's worth of a story featuring the characters a few years in the future, and Sabrina became an amnesiac in a contrived coincidence, grew fairy wings, was hunted and on the run from Fairy society, married Puck and became a princess, and True Love's Kiss brought all her memories back and then she remembered she hated him and there was Drama. I loved every moment of it. (Unfortunately, I don't remember the fic's name because I'd love to go kill revisit it.) That was probably my first encounter with a Sue.

The first time I really learned what a Sue was, though, would probably be when I came across the term while reading reviews for a Fifth Marauder story, and I resolved to never, ever, ever make the same mistakes. That... turned out about as well as can be expected. At least I was actively trying to avoid writing a Sue, so I think my story wasn't too terrible for a first attempt at writing?

It was about two years after starting my badfic series that I found the PPC, really got a feel for what did and didn't make a good story, and finally killed my old shame.

So for me, it was less of an "aha!" moment and more of a gradual realization of what made a Mary Sue.