I like to leave some things "blurry" in prose. Clearly CLB and I have slightly different ideas about how these folks look as well as some of the variations now coming in from you guys. I like that. It's part of what makes books unique as an art form.
Thymerae are what I call "Cthullu Monsters," whatever that means to you. I like the idea of a creature you'd normally run in terror from being the pessimistic guy you'd tell to shut up if he didn't stop with the buzzkills.
"aMershik. Dude. SERIOUSLY. SHUT. UP."
And who doesn't love Deltans? A species that can literally (and unintentionally) melt your mind by having sex with you (because it's just that awesome). They needed a mirror image so that's where Thymerae come from.
No one wants to have sex with them. Not even other Thymerae.
So Peya Fell and aMershik constantly having to work together (and being assigned together) from being academy room mates all the way to their post on TITAN just seems funny to me.