Nature vs. Nuture
I think I've kind of figured out what this is supposed to be about. The "good" Trumpy and the "evil" trumpy were exactly the same when they first hatched. They were neither cute nor murderous. The difference is, the first thing the evil trumpy saw was a human smashing all of the other trumpy eggs. From then on most of the humans he met attacked him on sight. This caused him to want to kill every human he met.
Meanwhile, the good Trumpy was raised as a pet, which caused him to grow up into a sort of E.T. ripoff.
LiLWingédPotato