SWORD ART ONLINE SEASON 1 EPISODE 10-CRIMSON KILLING INTENT
Kirito dueled Heathcliff with a condition of being a part of the Knights of Blood guild if he loses. Heathcliff was strong enough to beat Kirito. So, Kirito joined the guild, remembering, and blaming himself for all the sad events that happened with his past guild where Sachi was.
In the new guild, a member asks Kirito and Kuradeel to join him for a mission. Kuradeel apologized for his rude behavior with Kirito and went on the mission. When they settled down for break, Kuradeel appeared to be stranger who was with the audience on episode 8 He poisoned Kirito and the other member of his guild, then he killed him and was about to kill his target Kirito who was paralyzed with the poison.
Asuna came as fast as wind and saved Kirito at the last minutes. Kirito then sacrificed his arm to kill Kuradeel and save her. There true love between Kirito and Asuna started to appear, they spent the night talking together where Kirito promised her to live peacefully in a very nice place on floor 22 after they get married.