And that's what I like in this solution. Sable never betrayed Drakan, but still has something that connects him with "best milf waifu in the game" Nidhogg.
I´d argue that he already had that connection, due to dating Drakan.
I would be extremely surprised if Nidhogg would even register Fafnir as a living being in its own right, nevermind having any actual consideration for her.
I can only imagine how Drakan will be jealous in the sequel and how Nidhogg will react when Fafnir will get her body.
Oh, she will totally be jealous. Fafnir will require a LOT of Sable´s attention and affection, and Drakan will feel that she is being "stolen", so to speak. And both girls, being, you know...
draconic... are very likely to be not only possessive, but not really able to understand the concept of sharing.
And that is BEFORE we consider the following possibility:
Fafnir, as of now, is a purely spiritual entity. Whatever feelings she has for Sable now, are purely platonic/spiritual/moral.
Once Fafnir gets a a flesh and blood body, chances are that she will get the bagagge that comes with it, namely, hormones and feelings of the... you know... carnal... variety. She is bound to have some VERY confused reactions to her "dad", thats for sure.