I'm purposefully downplaying his advanced age in what I'm writing now, to make him seem more like Telemakos's contemporary and foil.

technically Lleu and Goewin are 11 years older than Telemakos. So that means, if you can believe it, that Goewin is only 22 by the end of The Sunbird. I think she seems older because you see everything from T's point of view; eleven years is a much vaster gap between 11 and 22 than it is between 16 and 27.