The fallout from the duel is understandable, since Helene’s dad knows how the game is played and Pierre doesn’t even know the game exists.
Basically, gossip about it spreads, but the spin ends up blaming Pierre for the whole thing and making him out to be some kind of crazed jealous monster. Helene is not a bad player herself: she instinctively does a resigned, uncomplaining martyr act that makes everyone feel very sorry for her. Oh, and check out how we still don’t know whether she did or didn’t cheat on Pierre. At this point is obviously doesn’t even matter anymore.
Anna Pavlovna is having one of her regular parties for fancy people.
The interesting guest this time is Boris, who is quickly rising through the ranks of the army. He's good at befriending people who can help him in some way – and he’s handsome, well-dressed, and well-spoken to boot. His whole life now is ambition and drive, and he’s totally forgotten about Natasha and the Rostovs.
At this point the Prussian army has been defeated by Napoleon, and the Russian army is fighting him off at the Russian border.
The party mood is resolute in the face of Napoleon, and Boris immediately picks up on what he’s supposed to be doing there – singing for his supper, basically. He’s the entertainment. He tells some great stories about the VIP he adjutants for, and about the court, and does it all without ever revealing his own opinion about anything.
Afterwards, Helene seems really into him and asks him to dinner at her house the next night. In private, Anna Pavlovna tells Boris about Helene's terrible husband.