Zia Simpson is one the latest characters to be made from The Simpsons so no she is not a fan made character. She is an Official Character. She is the daughter of Lisa and Millhouse in the latest episode of The Simpsons.
HAHAHA, you know what? I knew it would happend. I hope they make more episodes about Lisa x Milhouse, because I like this pairing. I just love the episode "Homer_Scissorhands". It is actually now my favorite episode. I mean,Lisa Simpson is actually jealous!! And she kissing him and said, that he is cute in the monlight. I always knew they get married. ^_^