User blog comment:Hereticalthoughts/The Seathe & Gwynevere Theory/@comment-24246053-20141022124208/@comment-18016240-20141022192007

In a different blog of mine, the topic of someone going from one race (Gwyn's folk) to another (human/undead) was brought up, but I reasoned there that it appears to be impossible to fully become another species/race, thus I don't believe Seathe would be able to change forms.

Even if he did, there's no reason why he would bother to or why he would choose Gwynevere. His research is entirely based on the scales of immortality and how one can achieve it, turning into a giant and having sex with Gwynevere has little to no bearing on that goal as far as can be discerned.