Board Thread:General Discussion/@comment-25365147-20150501040850

This was a theory I had a few weeks back, but "Reformed" seems to offer evidence for it. Amethyst changes form several times, often getting strange and eventually chaotic. When Centipeetle's bubble pops, she takes a humanoid form before becoming the monster. It's somewhat similar to when Pearl reforms, where she takes a few different shapes before taking her final one. It's possible that Gems turn into monsters when they're under intense emotional distress. It's implied that Garnet, Rose, and Pearl were the only normal Gems remaining after the war (Amethyst was found later) which would suggest that the Gem monsters we know got that way before or during it. And war is pretty intense. Maybe some Gems couldn't handle the pressure, maybe it made others crazy and feral.

We also know that Gem monsters aren't always entirely monstrous. If becoming a monster is based on emotional state, then that would explain why some monsters behave differently. Centipeetle, we know, was tamed fairly easily and grew to care for Steven. The lighthouse Gem never attacked anyone until it was hurt, and even then, it only directly went after the one who hurt it. Even the underwater monster was more interested in the glow bracelet. 