Cerberus, the hellhound and gatekeeper of Tartarus (and all-around good boy) is back in Hades 2, but not in the way you'd expect. It turns out that, when Chronos took over the House of Hades and imprisoned Hades himself, he cast Hades' most faithful servant (AKA Cerberus) out into the Mourning Fields. Out there, the spirits and residual negative emotions stuck to Cerberus like glue, and he's become sort of 'corrupted'. It's up to Melino to save him from this fate the only way she seems to know how, and that's by beating the problem up until it's fixed.