#despite the circumstances Bill is happy they aren't in danger of the nightmare realm

[jelloteeth]

Wait if the twins exist in the 3rd dimension, how DO they survive??? Like, does Bill possess them occasionally to get them away from danger? Does Bill possess some folks to take care of the twins? Do the twins miss being in the nightmare real or do they even know about it???

(I do think that bill as much as he hates the twins being in another dimension he prefers them being there than the nightmare realm since that dimension is slowly breaking apart)

So I'm still figuring some things out but-

The twins were born in Gravity Falls, they cannot leave its vicinity. So no Nightmare realm.

When the twins are awake Bill is very limited in how he's able to interact with them. From the book we know Bill can poses animals freely (unless I misunderstood that whole rat thing), unlike having to make a deal with people.

So I imagine most of the time Bill is following the twins as some sort of animal, like a bird or maybe a deer (though the bigger the animal the more tiring it would be for him). Most of the time Bill just watches them. If there's some kind of danger; dangerous animal, human, or something else- Bill would intervene with whatever animal he's possessing- or he would possess the danger if possible or scare them away. For food and shelter he would have to end up possessing animals (or people) for that as well.

When the twins are asleep (in the mindscape), Bill has total control over everything. Because of this he tries to keep the twins asleep as long as possible- though he usually doesn't get that long.

As the twins get older they develop the ability to 'shapeshift' somewhat, and are able to take a human form (Fords genes came in handy lol). This is both good and bad as they can help themselves more, but they also get into even more trouble now that they can 'properly' interact with people.

Also Bill is unable to posses the twins, its likely to do with them being the same species as him.