Well, I don't usually do time-traveling lines but when I've played Astoria, it's been as someone who is kind of the anti-Pansy, in that she's very into pureblood society but anti Death Eater, and I usually have her finding Pansy and Draco kind of uncouth and distasteful, so when I've played her against a Draco there's usually a fair bit of banter.
If we wanted to play post-War, the line could easily go snarky and cute or dark, depending on what you're looking for.