(I am considering which anime/shows/book to base it on but I've yet to decide completely but if you have any suggestions let me know and I'll see if they might work)
Celestine: A hybrid of a Water and Black Dragon given to Maulketh by Poseidon when she was still an egg. After feeding on his mana she had gained powerful fire abilities as well. After spending decades in a Time Formation she had matured along with her friend Astrid.