Guapo and Fraz are a species of bird-based alien.
For starters, there's the fact that they have pointy noses that resemble beaks. Then there's the episode "Thanks for the Memories", which is where the basis for this WMG comes from. That episode not only shows that the Flubs lived on a planet where the houses seem to resemble birdhouses, but also shows that they hatched from an egg. If the series continued, Fraz may have turned evil at some point.
The whole series seems like a villain origin story for Fraz. He is treated horribly by his boss, his co workers, everyone he meets on his deliveries and even his own brother. He constantly blames his brother for everything and wishes they weren't brothers. What if Fraz finally snaps and becomes the villain of an episode?
Mr. Doom created Guapo.
Fraz was meant to hatch on his own but Mr. Doom created a twin for Fraz, Guapo to make him miserable and it worked... For the most part. Guapo still had an undying love for Fraz and Fraz loved him back.
