Of course he's talked with Harry. The lack of surprise doesn't make it any better to hear, which in of itself is probably not really a surprise. Things have been tense, with Harry. Things have been good, and bad, and somewhere awkward and in between, but at the end of it, Harry is still James' kid, still someone Sirius feels some loyalty to, no matter what else. And Harry can't have offered a tour. Even Harry wouldn't offer Snape a tour, he's James' kid.

James' kid. James, and the lack of him twists again at Sirius, deep in him, somewhere visceral and painful, and he moves closer toward Snape again, like he's going to grab him by the collar again.

"Just shut up." The words grit out of him, fiercely; if he doesn't shut up, Sirius will hit him, again, he wants to hit him all over again, like somehow that will make up for James being gone, like somehow that was Snape's fault-- "Shut up. Now. Why the hell is it you Why is it you here, and this fucking ship, it's-- brought you instead, why the hell is it you?"