#snakes stuff

From the outside it seems like they both have the same goal, which is to be the most powerful being there is. But they both have very different motivations for wanting that.

Vox is driven by ego. He can't stand it if theres someone better than him. and as a foil to charlie he needs people to witness and acknowledge that he's the best.

However Alastor needs to be the most powerful because it secures his freedom and safety. We haven't explicitly gotten his motivation for killing in his lifetime, the common speculation is that he targeted racist assholes who crossed him. Those kinds of people would have certainly posed a genuine threat to not only his career but his physical safety.

When he makes the deal with Rosie, I don't think it's just because he wants to avoid suffering in hell. He knows all his victims are waiting for their chance for revenge as soon as he dies. He securing safety for himself by making the deal.