How did he get here?
I have this part all figured out, so try and follow me on this one. The black cat used to live on the planet Blacatika, right? So, he had to leave for a reason. I used to think it was either that he was 1) Ejected from his planet, 2) Sent to make Earthlings intelligent, 3) The only survivor of his blown up homeplanet, or 4) He was sent to takeover Earth.
Now, in detail. I shoot down 3/4 of the above. 1) Would you look at him? How could he commit a crime? He's too cute to do that. 2) He's a more dominant race, intelligence wise. Why would he want someone to rival his intelligence? 4) That little body isn't capable of fighting. Sure, over thousands of years he could do this, but by then he'd be institutionalized on Earth. This only leaves one that doesn't have any chance of being shotdown. Number 3. I have some reasons for why number 3 is the one I believe is correct. For one thing, he's the only one of his kind seen in the series. If the planet blew up, chances are that the rest of his race went with it. Another thing is that this would explain him staying on Earth for so long. He crashed on Earth in his space pod and it was so banged up that it could never be used again. He was forced to adjust and take over a body, a Briefs family ancestor. These reasons tell me that he's the last of his kind, do to mass-extermination via a planet explosion.
To better explain this theory of mine, I drew this picture in my cheesy, generic brand jpg editor. I hope it will shed some light on this lidea of mine if you had a hard time comprehending that which I typed above (you probably did). Enjoy.