I very much doubt he's Thaliak. Thaliak is a scholar and bringer of knowledge but he's not (supposed to be) solitary. At least, not as obsessed with being alone as Deryk seems to be. There's also the whole thing about the small animals being the 12's forms when they don't fully reveal themselves and it looks like his may be a fish which you can see in Omphalos swimming.

I hope Deryk doesn't have a god complex but... We shall see