It looks like the same outfits from the cover. And by looking at the blue sleeve I'm pretty sure it's Keefe. So yeah it also looks it's by a tree so I guess it's Callas but I don't know.

BUT YA YA YA HOPFULY ITS KEEFE!!!!!!!!

Wait I keep on forgetting it's a flashback scene ...

Oh but wait! But what if it's that end part where Fitz thought he killed his brother and Sophie needed a break and left that room and went and sat down on a trunk I think along with Keefe...

But hopefully not the scene with fitz telling her shes BEaUtiFuL like ilovekotlc thinks it is.