An additional idea for why Alastor ended up trusting Pentious, during the early days in Hell sometimes Alastor forgot he's dead and thinks he's in a dream, therefore actually helpless to save himself from the predators
One time during one of his less lucid days he was running away from a predator and got cornered in an alleyway, and just as he was about to be mauled by the predator, who should save him but Pentious, who saw someone in a dress about to be assaulted in an alleyway and possibly killed afterwards, and couldn't stop himself from flashing back to his living days, and he decided to save this little deer doll
That sounds likely! Sir Pentious saves the wandering confused child and declares, "I'm a dad now!"
He probably assigns at least half the Eggboys to watch Alastor whenever he himself can't be there, and Alastor enjoys playing "Hide and Seek" with them!
