The Devourer and The Assasin.

Gustavo is a huge saltwater crocodile who spent over 60 years in a zoo. He spent his days relaxing in a huge pool for himself, yet that all changed when the world ended. A virus from space wiped out over 60 percent of all life and the survivors evolved. Gustavo was freed by his handler and the two must work together to live in this dangerous new world.