“The Survival of the Fittest” is episode ten of season two of The 100.
After the events of the previous episode, “Remember Me”, the Grounders and the Sky People have finally allied with each other, although not without friction, against Mount Weather, and Raven accepted to at least some degree Clarke’s killing of Finn, after seeing what would have happened to him otherwise and how painfully he would have died. The others of the 100 still in the mountain finally managed to communicate with those outside.
Bellamy is going to get into Mount Weather, with Lincoln’s help, through the Reaver tunnels. Octavia demonstrates stubbornness to a degree that gets her respect from one of the Grounders opposed to the alliance. Lexa and Clarke end up running into one of the more dangerous examples of surviving, and mutated, wildlife, and former chancellor Jaha starts making friends with Murphy, with the intent of making his way to the City of Light.