I suppose the ideal pet would be an Ego. Called Bob. If you could feed him once a day (or three small feeds on a PMT day), life would be altogether more pleasant. Like most perfect pets, Bob would probably crave exercise most when you're tired (of being spiritually sound). He's easily entertained (by moments of self-delusion, ambition and wayward pride) and only gets cranky when provoked (by People Not Like You). And while he might serve a purpose to get things done (kill rats, gobble blow flies, wee on unwanted suitors) it would be so nice to just be able to say "Back in your box Bob" without hurting anyone's feelings (least of all yours).