*prepares herself to be shot down*
So pets can die, and then to bring them back, you need to go on the reviving quest *forgets what it's called*. Okay, you need a Blessed Flower or two to bring it back *please bare with me peoples*. Uh oh, you messed up the quest somehow! You did something wrong, and now you pet comes back in the form of a zombie/ghost thing!
Idk, this is a weird idea, but if the story above was too vague, then what I'm suggesting is an alternative to the Reviving Quest thing. Instead of bringing back your pet with the required items/things/stuff, you'll used some other item or something, maybe a Cursed Flower (to complement the Blessed Flower), and it brings back a ...... Otachie, for example, with ghostly or zombie like attributes.
This is just an idea for fun. xDDD I can understand if it gets shot down, but I suggested this as an alternative to hatching colors, beans, and dye kits. It'll probably be a lot of work for the artists, though..... ^_^;
[Edit]
If I can, I'll see to I can provide a (poorly) drawn example...