What are you guys' thoughts on Princest? I used to be against incest before I got into the fandom (oldfag here from 2011), but not anymore. I don't know if I've just gotten perverted over the years or if my mind has just been opened up, but I have no problem with incest in general so long as it's between consenting adults. All that aside, I think Princest is pretty plausible. Here's why:

1. 1,000 year separation - that's a long time for the westermarck effect to fade away.

2. Seeing they're both immortal, it would make sense that they would seek a more permanent relationship after losing so many lovers in the past.

3. They're close - I don't think there's many secrets between the two sisters.

4. They live and work together - that's a lot of togetherness and a lot of opportunities for something else to form.

5. It's probably difficult for them to find mates - being Princesses and all makes them unapproachable, and they have to keep up appearances so they can't just go out with anypony they want. I can imagine the frustration they must feel, and they probably share their frustration with each other at times. It wouldn't take too many nights of this before the topic of "helping" each other came up.

Maybe it's romantic, maybe it's just sexual, but I can't imagine them not having sex with each other at least once - if nothing else but to scratch the itch. What do you think?