The Old Ones

When Castiel was returning the Monster Souls back to Purgatory, he decided to not take the chance on anything escaping and jumped into the void too. Receiving some help from a higher power, Castiel was whisked to a area almost as messed up as his world. Helping a pervert in need, Issei and Castiel will show that universe true power. Grey Leviathan/Seraphim Empowered Issei.