(a joke theory that is kiiiinda supported by canon)
Anyways. We all know that Godwyn and Fortissax were bros, right? I mean, Fortissax fought the death in his body until they themselves were corrupted, which indicates pretty damn strong devotion for an ancient dragon.
With that being said, here's my proof.
-Fortissax's rememberance lists Godwyn as their 'companion', which seems like a light word to use for someone who fought the death within him until they themselves were corrupted and turned into a mindless lich that STILL continued to guard his corpse even after Death rooted itself in them
-Fortissax's sister was Lansseax, who was known for concealing herself as a human to lead the dragon cult in Leyndell. She loved Vyke dearly, too, so it's not really improbable that Fortissax might have done the same
-Fortissax and Godwyn don't really need to have strong romantic ties between them because it's very likely that dragons don't really do romance the way we do. It could have been a fwb relationship on Godwyn's end and an actual mateship on Fortissax's end and it probably would have worked just the same anyways. I mean, they're dragons, what are you supposed to do, marry them?? There's no way in hell they'd take the concept of a wedding ring seriously
-Godrick's line when speaking to the corpse of the wyvern in his arena is 'Oh mighty dragon, thou art a trueborn heir. Lend my thy strength, oh kindred', which yeah it's supposed to point to how he's this runty little thing that's a shadow of Godwyn's glory who's talking to a similarily runty little thing that's a shadow of its ancestor's glory in a fucked up perversion of Godwyn's allyship with the ancient dragons, but also what if it was canon. What if Godrick's ancestors had dragon blood in them, and that's what makes him even more of a dissapointment, for the ancestor of a demigod and a dragon to be so feeble
-Information about Godwyn's lineage is surprisingly shady for someone who's technically super important and prestigious. Which isn't really a surprise, because the effects of Godwyn's death far outweigh any importance of Godwyn himself, and we're supposed to feel that in-game, but also what if it was very hush-hush for a reason. That reason being that Godwyn fucked a dragon. Marika def. wouldn't have liked that, but it's not the first time that shit's been hastily covered up with this family (cough cough the omen twins cough)
-Fortissax is referred to as an 'it' in lore, while their sister is a 'she'. This is probably just because they're a dragon so gender doesn't really matter, and Lansseax went out among people so she probs got the gender virus by proxy, but that doesn't close the possibility of Fortissax themselves being impregnable
-Even if fucking a dragon wasn't really something that the Golden Order would have liked, Godwyn having heirs with the dragon who was once known as the 'mightiest boulderstone' that hailed from the previous rulers of the Lands Between certainly would have been a much better match for the son of Marika and Godfrey than some random person who never got a mention in lore (as we know pretty much everyone else's husbands or wives are notable for some particular reason, and you can only become Marika's consort through a show of great strength/after you take the throne as Elden Lord)
Case in point: Godwyn fucked a dragon and Godrick is the descendant of Godwyn fucking a dragon, which is why he can graft a dragon head onto himself despite all his other grafts being relatively humanoid