That Breeder is the King of Fantastic Beasts

Tarik, a lowly stablehand at a magic academy, abandoned by his family since childhood, unexpectedly rescues a baby unicorn and binds it in a soul contract. Trapped in the desolate borderlands, his true identity is torn open: the supreme bloodline of the "King of Beasts" awakens within him, and he finally reunites with the kin who cast him away...