[ Yeah, that's not a surprise. ]

Not 'a' trench. Just Trench. It's the city that Stanley, Dipper, and I lived in before we arrived here. It was similar to the Grove, in that it was another dimension that ended up drawing many people from other dimensions towards it.

[ Which is probably simplifying things, but they don't really have time for much else. ]

And while we were there we... met Fern. Not you, but another version of yourself.