As for the sisters, I don't really remember too much about their general personalities, except that Chloe was the sweet, perky one, Marie was the most responsible one, and Valerie was still in high school and very weird. As part of the RP, Chloe hooked up with Archibald, and outside of the RP's canon, Marie had an on-again-off-again boyfriend (which was my younger self's idea of character humor, since Marie was otherwise very set in her ways).
Actually, I'm not sure if those three came first or if they came after Enrico and Ocirne, characters I made for a Pokemon RP on the old TRHQ board. Again, I don't remember too much about their personalities, but they were twins. I made Enrico first, a Pokemon protector who could turn into a Chansey (though this didn't come up too much in the story), but later on his evil twin debuted, who was a villain and could turn into a Ghastly (though again, this didn't actually come up too much). They both had spiky black hair (to fit the Pokemon anime style) and (inspired by The Matrix), they both wore black trenchcoats. Being a villain, Ocirne was more interesting than his brother, so I remember more about him (though a lot of it was made by the other people in the RP, since it was kind of free-for-all when it came to using characters). He had a lair in Bermuda where he would relax whenever his plans failed, Jigglypuff from the anime series became his hench-mon (and occasionally turned into a real girl depending on the plot), and he had a smoking habit (which mostly manifested itself in his evil laugh being cut short by a coughing fit, followed by him commented that he really needed to quit smoking).
It was actually my older sister who named Ocirne, when I had just come up with the idea for Enrico to have an evil twin and couldn't think of a name. She suggested spelling Enrico backwards, and the result sounded like an evil name to me, so I stuck with it, and I still like it. Enrico was a name I just pulled out of nowhere (not knowing how long the RP would end up running, nor what large parts my characters would play), and my younger self was actually surprised to find out that it was a real name. My older sister also drew a fair amount of art of these two, at my request, though most of it now resides in forgotten sketchbooks somewhere (probably).
Update: Okay, I guess if I really wanted to talk about my very first stories, I'd have to mention that little books that I wrote in first and second grade (as school assignments). But the only one I remember anything about is one about a frog from outer space that I based on a Jeremy Fisher toy I had. I remember writing a number of stories, and meticulously picking out images from Printshop to use as cover images, though.