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If I didn't send you, they would have died on the Ark with the rest of us, and we would have never known that Earth was survivable. Their sacrifice is why we are here.
Thelonious Jaha to John Murphy

Survival of the Fittest is the tenth episode of the second season of The 100. It is the twenty-third episode of the series overall.

Lives are at risk as Clarke and Lexa encounter a new enemy. Bellamy and Lincoln agree to work together to break into Mount Weather. Murphy helps Jaha confront his past. Meanwhile, Indra makes Octavia an offer she can't refuse.


Bellamy and Lincoln are disguised as Reapers as they head toward the Mount Weather mines. Lincoln spears an animal and cuts it open. He smears blood on his face along with limestone to enhance his Reaper disguise. Lincoln tells Bellamy about the intake process and how each person is tagged for either Cerberus Project (like Lincoln) or for harvest. Bellamy mentions that his mom read mythology to him and Octavia all the time and that Octavia loved it, causing Lincoln to smile. Bellamy asks why he protected Octavia before he knew her. Lincoln then tells Bellamy how when he was a boy, a Sky Person dropped from The Ark in a pod and onto Earth. For three days, Lincoln tended to the man, eventually telling his father. His father made Lincoln kill the man and the world has been trying to turn him into a monster for as long as he can remember. Bellamy tells Lincoln, that he'd heard about people from the Ark doing that.

Indra arrives at Camp Jaha with her warriors. Marcus Kane makes them leave their weapons behind and invites them to a reception. Jaha tells Kane that this alliance is a mistake but Kane disagrees. While Kane is giving a speech about how this is a chance for Grounders and Sky People to work together against the Mountain Men, Penn starts accusing Murphy in Trigedasleng for being at the massacre in Tondc and not doing anything. Murphy tells him he doesn't speak "Grounder" and the two get in each other's faces. Kane gives Murphy two days of work detail and tells him to apologize to Penn. Murphy refuses and Penn tells him he's going to burn like Finn. Murphy swings a punch, which causes everyone to start fighting. Octavia and Kane trying to break up the brawl while Jaha watches smugly.

Clarke is back in Tondc, planning with Lexa and her leaders a way to get both of their people out of Mount Weather. Quint gets argumentative with Clarke before storming off, saying he can't be in an alliance with the Sky People. Lexa tells Clarke that waiting for Bellamy to get into Mount Weather is a prayer, not a plan. Clarke excuses herself for some fresh air and Major Byrne follows after.

Lincoln and Bellamy are on their way into the mines around Mount Weather. Lincoln tells Bellamy that he remembers everything from when he was on the Reaper Red drug.

Clarke is wandering around outside when she spots Quint tracking her. He starts to taunt her and shoots arrows at her as she runs.

Kane and Octavia watch the Grounders training and Octavia attempts to get Indra to let her train with the grounders, but Indra refuses.

Clarke pauses while running from Quint and sees Byrne whose arm has been ripped off. Byrne tells Clarke to save herself.

Murphy is busy mopping floors when Jaha tells him he got him off work detail because he wants Murphy to take Jaha to Wells' grave at The Camp and hands Murphy a gun.

Kane is working with the Camp Jaha Guards on the firing range when they notice Penn and a few other Grounders watching them. Kane offers to teach them but Indra interrupts and tells Kane they don't need their weapons. Octavia tells Kane that Grounders are scared of guns because of the legend that Mount Weather will wipe out their entire village if a Grounder ever touches one. Denby, one of the guards, points out to Kane that Octavia seems to know a lot about the Grounders.

Clarke is running through the woods when she is attacked by Quint. Lexa comes up and tells Clarke she can kill Quint when they hear a loud roar. Lexa says that it's a "Pauna" (a giant mutant gorilla) before she slices Quint's leg, telling Clarke to run. The Pauna attacks Quint while Clarke, Lexa, and her guard look for a place to hide. They quickly realize their hiding place is actually the feeding ground of the Pauna when she leaps over and attacks their guard. Clarke shoots at the Pauna but the bullets don't stop her and she chases after Clarke and Lexa, causing Lexa to injure herself. The Pauna grabs Lexa's leg but Clarke refuses to leave Lexa behind, saving her life even as they trap themselves into a room.

Jaha and Murphy are walking through the forest on their way back to the drop ship and Jaha tells Murphy he remembers his father; he remembers everyone he floated. Murphy leads him to the graveyard.

Bellamy and Lincoln have finally arrived at the entrance to the Reaper mines, Lincoln appears hesitant but goes on anyway.

Back at the drop ship's graveyard, Jaha is having a moment over his son's grave and asks Murphy how well he knew him. Murphy tells him the truth about how Charlotte killed Wells because she couldn't kill Jaha. Jaha tells Murphy they'll rest at the drop ship for a while.

At Camp Jaha, Indra commands her warriors to get ready to hunt because the Sky People don't have any food. As the grounders are about to leave Camp Jaha, Octavia stands in Indra's way and tells her to make her move. Indra calls over Fio to give Octavia the fight she is looking for. The Grounder, Fio, defeats her, but Octavia continues to stand up again and again until Indra calls it off. Kane helps Octavia stand up, asking her what she was trying to prove. She replies back, "what doesn't kill you makes you stronger."

Clarke and Lexa are still trapped in the room and Lexa tells Clarke that she's being weak by helping her escape the Pauna. Clarke tells Lexa that she needs her because she's smart. The Pauna finds them and begins beating against the door. Clarke has Lexa stand on one side of the door while letting the Pauna charge in and then race out the door, shutting it behind them and trapping the Pauna in the room.

As Octavia is recuperating from the fight, Indra appears and tells her that she fought like a child but Indra is willing to train her and take her on as her Second. Octavia agrees.

Jaha and Murphy are hanging out in the drop ship. Jaha tells Murphy that he deserves a second chance and that "good can come out of even the darkest acts." Jaha tells him how they're similar and are both outcasts by their own people. He tells Murphy about the City of Light and how he wants to find it and lead his people home.

As Lincoln and Bellamy make their way through the Reaper tunnels, Lincoln finds himself struggling with his addiction to the Reaper drug. The two discuss the plan to infiltrate their base and once again, Lincoln says he doesn't think he can do it. He tries to back out of the plan, but they're interrupted by another Reaper raiding party and Lincoln has to pretend that Bellamy is his captive to keep their ploy from being discovered.

After Indra and the grounders bring back food for the people of Camp Jaha, Kane acknowledges that it was Octavia who brought the Grounders and the Sky People together. Fio, the man she had sparred with earlier, brings her a plate of food. Kane asks her to "look out for [her] people," to which Octavia ambiguously replies that she is.

Murphy awakens to find a group of people outside the drop ship. Jaha had invited them to come with him to find the City of Light and now Jaha wants Murphy to join them.

Clarke awakens to find Lexa watching over her in the woods. The Pauna is still trapped and they are safe as long as the cage holds. This gives Clarke the idea of using all the caged Grounders trapped in Mount Weather as an army as long as Bellamy can get inside and release them.

The Reaper raiding party has reached the underground entrance to Mount Weather. Bellamy and the other captured Grounders are marked for harvesting. Lincoln is unable to resist the Red drug and allows Bellamy to be harvested by the Mountain Men.



Guest Starring


  • Luc Roderique as Penn
  • Arleo Dordar as Lexa's Guard
  • James Michalopolous as Fio
  • Sean Millington as Alpha Reaper



Bellamy: "I need to know what happens after the intake door."
Lincoln: "They remove your clothes, blast you with boiling water, and douse you with something that burns even worse. From there, we were sorted. The others were tagged Harvest. I was tagged Cerberus, turned into a Reaper."
Bellamy: "Cerberus. Three-headed dog that guards the underworld."
Quint: "This argument is a waste of time. It is simple if they can't breathe our air, why not just open the door and be done with it? Let them burn!"
Lexa: You should've left me behind. Now two will die here instead of one."
Clarke: "I'm still new to your culture, but when someone saves your life my people say thank you."
Lexa: "I'm serious Clarke, to lead well you must make hard choices."
Clarke: "You wanna know why I saved you? Because I need you. God forbid one of your Generals becomes Commander. You may be heartless, Lexa, but at least you're smart."
Lexa: "Don't worry - my spirit will choose much more wisely than that."
Clarke: "Your spirit?"
Lexa: "When I die, my spirit will find the next Commander."
Clarke: "Reincarnation. That's how you became Commander?"
Lexa: "How are your leaders chosen?"
Lexa: "Don't be afraid, Clarke. Death is not the end."
Clarke: "We are not dying here. I need your spirit to stay where it is."
Lexa: "Then get ready to fight, it's coming in."
Lincoln (to Bellamy): "The world has been trying to turn me into a monster for as long as I can remember."
Indra (about Octavia): "Even a fool knows when to surrender."
Indra: "You fought like a child today. All aggression, no thought, no defense. Always leaving yourself exposed revealing your next move before each strike."
Octavia: "Okay, I know. I got my ass kicked. That should make you happy."
Indra: "It does."
Fio (hands Octavia a plate of food): The boar put up a better fight than you."
John Murphy (to Jaha): "I'm nobody's son… You made sure of that."
Jaha (to John Murphy): "Good can come out of even the darkest acts, John."
Jaha (to John Murphy): "I have to think of everyone. I know you don't want to hear this, but sometimes you have to sacrifice the few to save the many."

Notes and Trivia

  • The title refers to a quote that originated from Charles Darwin's evolutionary theories. It describes the concept of species that have adapted best to their environment having the highest means of surviving. 
    • This is demonstrated by Clarke Griffin and Lexa killing a gorilla in order to survive.
    • The title may also be a reference to the evolution of the Sky People, Grounders, Mountain Men and Reapers due to radiation.
  • Murphy's father's name was Alex.
  • Goof - The gun Clarke was using can only hold a maximum of 6 bullets with its standard magazine clip. The only other magazine clip for that gun would hold 10 bullets. Clarke shot approximately 15 or more.
  • We learn that Bellamy knows his mythology when he speaks about Cerberus with Lincoln.
  • This is the first episode of The 100 that Thomas McDonnell does not star in.
  • This episode marks the first time Marcus Kane and Octavia Blake have an interaction/conversation.
  • Lexa mentions that her spirit will choose the next Commander when she dies. This is later revealed to refer to the Flame AI that all of the Commanders have in their heads which saves the consciousness of each dead Commander.

Body Count

Behind the Scenes

  • The title Survival of the Fittest is a reference to the evolutionary theory to describe natural selection. It can be loosely interpreted as 'Only the best suited to their surroundings will survive.'

Production Notes




Song Title
Song title here Album title here Artist name here [Purchase link here]



See Also