Knowing he is about to turn to a walker, Lee gives Clementine some last pieces of advice and tells her to meet Omid and Christa, and then asks her to kill him (a choice left to the player).
He is about to turn to a walker. This was what Lee was knowing. Lee gives Clementine some last pieces of advice. Lee tells her to meet Omid and Christa. Lee asks her (a choice left to the player). This was to kill him.