When Hades and Persephone retired, Phosphorus (better known today as Lucifer MorningStar) expected to be appointed God of heaven, and was absolutely livid when he was passed over for Vatru MacBean, he felt that as someone who was closer in relation to Hades (buy a slim margin), he should've gotten the gig. Of course, he rebelled, and failed to become God of heaven, and was banished from heaven.



Because he didn't want to go too far, and he just did not care for Kitenadro (too small of a territory), he went to hell, and because he was still in a overthrowing mood, he overthrow and murdered Hel, and became the third god of Hell.

(this is very much like how Jeffrey Kattenburg expected to become President of Disney after the untimely death of Frank Wells, but when he was not, he left and started DreamWorks)



Anyways, Lucifer ruled over Hell until his death which was caused when he (and there's no nicer way to say this) cucked Leonard and fathered Leviathan. Leonard found out, got angry, and ran him through with his horn.