Watanuki had considered getting a pet once, back when he was still relatively young. At that age he would get occasionally lonely, all alone in his apartment. He didn't want to bother the owners of the apartment more than he had to, but occasionally the room would feel too big for him (just him) and the idea of cooking and cleaning for only one would make him feel terribly lonely. Having something else there to care for would most likely make things easier.
Still, if there was one thing Watanuki had become (other than an orphan), it was practical. Thoughts like 'who's going to take care of it while you're away at school?' and 'the money mom and dad left isn't going to last forever, and pets are expensive—money for shots, food, trips to the vet, toys and the like isn't going to come out of thin air. Are you willing to put so much of their money to this commitment?" came quickly to attention. But what was even more important, what decided it for him, was the knowledge that, eventually, his pet would die on him.
He hadn't thought he was ready (would ever be ready) for the stench or the loss.
The pipe-fox spirit nuzzled his cheek before winding down the length of his arm, its fuzzy ears tickling his palm. He can't help the bemused smile that crosses his face as he switched the ladle to his other hand, the rhythmic stirring never stopping as he moves the fox back to his neck. It loops itself there, cuddling closer, and the irony is not lost to Watanuki.
He had avoided getting a pet because eventually it would turn into a spirit, but the one he has now is just that. He doesn't mind it that much.