[s1e6] His — Sister's Keeper

: Flashbacks show Bellamy assisted his mother during Octavia's birth and promised to keep her a secret from the Ark's authorities.

: It is revealed that the Grounder who took Octavia, Lincoln, actually protected her and healed her leg.

: While searching for a missing Octavia in Grounder territory, Bellamy, Jasper, and Finn are confronted by Grounders.