It hadn't taken Buffy long to figure out where Dean would've taken Faith-- there were limited options, after all. His principal haunts tended to be either the Impala (not great for tending the injured), her own house (he wasn't there, obviously), the Bronze (just... inappropriate) or the place where he lived, which she easily located after a minute or two of map-scanning, even if she'd never visited.

So here she is now, (looking pissed as hell by the way) knocking on the door and calling "Dean? Faith? It's me."