There are. A lot of Yu - Gi - Oh GX fans are into creating their own original characters and pairing them with existing characters like Alexis. The fanfictions can range from short and sweet stories to long, multi - chapter epics. Some might explore a romantic relationship between the oc and Alexis, while others could be more platonic, like a friendship formed through their shared love of dueling. You can often find these fanfictions by joining Yu - Gi - Oh GX fan communities and asking for recommendations too.
Yes, there are some. You can start by looking on fanfiction websites like FanFiction.net or Archive of Our Own. Just search for 'yugioh gx oc x alexis' and you'll find a variety of stories written by different authors. Some might focus on adventure, while others could be more about the relationship between the original character (oc) and Alexis.