So Kaz's whole deal is that he can't fall in love with mortals. If he falls in love with one, he loses his immortality and he can't go home. Which he's not a fan of, because Kaz has dreams of being king. He can't do that if he's banished....Klaus was the first person Kaz lost his immortality to.
OOF THATS SUCKS POOR BABY KAZ I AM ON THE JAZ TEAM I HAVE FALLIN IN LUV WITH BOTH OF THEM (not in that way in a like way) AND I HOPE THAT THEY BECOME AN OFFICIAL THING WITHOUT ANYTHING HAPPENING TO KAZ T-T SO MUCH CHARACTER DEVELPMENT I NEED THIS AS AN ANIME AND A MANGA