I'm getting good, no?
Chupa, he was assigned to be a scout along with a few other invaders of the Irken race to go to Earth, Columbia, just to see if it was possible to invade. Just before they were due to leave, it started to rain. Chupa was caught out, burning him badly. The rest of the team took off without him, and, with his SIR on the ship and his PAK malfunctioning due to the rain, also accounitng for his physical change, he was left behind. He headed north, as he'd seen civilisation that way from the ship.
A few days later, he came on a villiage, starving and dehydrated from the desert. The nearest creatures were the villages goats, so he had no choice but to attack and drain one of the goats dry. He fled when the 'filthy monkeys' found out, but has been living like this for a while, as there is little food, waiting for some recognisable sign of Irken rescue. The locals have dubbed him 'Chupacabra
' for his feeding tendancies.