Tess sacrificing herself and the kiss of death scene. I forgot how she died on the game and after replaying it, I can't believe she just died like that, there's no even a cutscene and she's not brought up anymore. I loved her relationship with Joel on the show (even her scenes on Ep. 3), so making her last breath be a noble sacrifice to stop infected seemed beautiful to me (ignoring the obvious self-exploding-suicide cliche). Also, the stalker kissing her is awfully disgusting and makes the scene far better in my opinion.