He originally wanted him to be a Stank Ass #6, but chose to name him Priority Mail instead. At the end of Episode 71, he said he was going to tame a white cat and have him and Priority Mail fight. In Episode 72, when he finally tamed and named the white cat Stank Ass #6, he described them both as "Yin and Yang" because of their colors matching the symbol. When Nova was going to find and tame a Panda he ended up going around in a circle starting in his garden, then the big mountain next to his garden, then to the little forest, then back to the house Sly built for all of them. He ended up noticing that Stank Ass #6 was sleeping on a part of the big mountain and then came down to "protect" the garden from insects like dragonflies and flies. Nova then ended up noticing that Priority Mail was gone. His first speculation was that Priority Mail drowned himself, then he speculated that Priority Mail climbed to the top of the mountain but Nova didn't go all the way to the top. Because of this, Sly and Seamus joked that Priority Mail was sent somewhere else because of his name. They all then had a good laugh about that. It is still unknown if Priority Mail will ever be seen again.
At around 12:40 in Episode 72 of the series on Nova's Channel, he notices a fox fighting an unknown creature on the roof of the house Sly had made for them. Unbeknownst to him, the unknown creature was Priority Mail. Priority Mail did not survive the fight with the fox.
Priority Mail had faked his own death, as he returned in Episode 74.