I am not really sure.

I like the Trix and I hate Diaspro. And if Diaspro joins the Trix, then they won't be the "Trix" anymore.

Not exactly join them, more like work with them.

Maybe like an evil fairy or something.

Actually, but I actually think, the Princess Diaspro from Eraklyon should be yes the witch, but maybe the Trix think about her future against their archenemies, the Winx, but otherwise currently the same Diaspro is actually the "fairy", and at her own class, the "class of fairy", unlike the "class of witch", it would be her new class, as a witch but just with her "Dark Witch Outfit", and as the "dark witch", but if she doesn't join them, but maybe she gets revenge alone, but against her "official" rival, the Bloom, Daphne's younger sister, but for Bloom's fience and her former arranged fiance, the Sky, formerly the prince and currently the king, but at Eraklyon, her, Sky's and Brandon's homeworld. And above all, both Sky and Diaspro are as blonde ones as Stella, Daphne, Roy, Bloom's foster father Mike, Queen Luna and Countess Cassandra, of course, Stella's rival Chimera's mother.