- "Maybe there are no good guys." --Abby
The 100 challenges its viewers' morality by allowing the show's protagonists to make questionable decisions. It's up to us to determine how far our goodwill reaches, and how much it takes before a character's past crimes can be forgiven.
It's very clear that, although everyone on The 100 (with the possible exception of Raven) have done some shady and/or mass-murderous things over the course of the show's three seasons, our main protagonists ultimately want to do the right thing. But the further we get into the brutal world of the show, the less the characters are concerned with doing the right thing, as opposed to doing the right thing for their own people. In that sense, Shatner is right — after all, even villains usually see themselves as the heroes of their own stories.
It's not just the characters that are left wondering whether their choices were right, the viewer is forced to ask the same question. Would we go to such a dark and brutal place? Could we? 
Even the antagonists are never truly "evil". When it comes down to it, they use the same reasoning as our main characters to justify their actions 'I'm doing what's best for my people'. Dante Wallace, despite being the leader of Mount Weather and allowing his staff to experiment on grounders, tried to protect the Delinquents on several occasions, as long as his people remained safe and secure. In the final episodes of Season 3, Mount Weather has already been compromised. Only then does he allow Cage to drill the Sky People for bone marrow, as his final resort. This can be paralleled to Season 4, when Abby tests Nightblood on "Baylis", and almost on Emori, to save their people from Praimfaya. In both situations, the leader has taken the lives of innocent people, in order to save those of their own. In "The 100", the lines between hero and villain are blurred, and often a matter of perspective rather than true morality. However, A.L.I.E., the major antagonist of Season Three, is purely evil, and has no remorse of killing innocent people. This is debatable, as A.L.I.E.'s plan was to make life better, human life is not the only type of life worth valuing.
"The 100" doesn't pretend that its protagonists are heroes. It never glorifies violence, no matter who is perpetuating it or however valid its logic is given the protagonists' goals. Even when "The 100" convinces us that we would probably do exactly the same thing in these characters' terrible positions, it never shies away from the unbearable weight of it all.
This perhaps best exemplified in Blood Must Have Blood (Part 2), where The 100 show its protagonists do terrible things in the name of saving the ones they love, having Clarke and Bellamy kill every man, woman, and child in Mount Weather to save their people from Cage's bone marrow harvesting. This includes Maya, the girl who made their continued survival possible. It includes all of the Mountain Men who harbored Sky Teens at risk to their own lives. It includes the many innocent children who called Mount Weather home. This decision isn't presented as the only option (because there are always other options), but it is presented as necessary if Clarke and Bellamy want to save their loved ones -- and this is an important distinction. In the following episode, Wanheda (Part 1), interesting subtext comes into play during the Niylah and Clarke story. While Clarke is burdened with guilt over the events of Mount Weather, Niylah sees her as a folk hero of sorts. Not only does she protect Clarke from Grounders searching for her, but she tells her that she supports her previous deadly decision. "You ended the reaping," she says. It's an interesting and complicated thread, about how violence and war creates heroes, villains, and antiheroes, and hopefully the show unravels it further as the season goes on.
- "Who we are and who we need to be to survive are two very different things" --Bellamy
The idea of who people are and what makes them who they are is a prominent theme throughout the series, becoming more prominent as the series goes on. The 100 has never been about vilifying people because of their actions – however horrible.
This perhaps best exemplified in the character of Bellamy, who goes through a number of changes related to power, morality, and loyalty since the show's beginning. Notably in his Season Three finale explantion, of his partially responsible for the massacre of 300 Grounders, in that he needed to think in black and white terms in order to survive in a world that's anything but, and now all he can do is work for forgiveness.
Free will and the loss of one's agency has been a recurring theme on The 100 since the beginning. 
Unlike many shows, sex and sexuality isn't a dominant theme on the 100. For example, it's the aspect of love and intimacy, rather than lust and sexuality, which makes Clarke's part in Finn's demise so difficult–the show plays with the idea that human connection, whether it's through friendship, family, alliance or romance, is painful because it matters, not because it is fundamentally wrong.
In the futuristic world of The 100, discrimination has become a non-issue. The only way to differentiate between people is what clan you're part of. Everything else just simply doesn't matter. It's the shows modern approach to gender, race, and sexuality that allows us a wealth of well-written characters, both male and female, who encompass violence in different ways.
The show has an impressive amount of women in leadership roles, and much of its exploration of violence is around the lengths they will go to ensure the survival of their individual communities. In the world of The 100, which seems to be implicitly a world which has moved beyond modern prejudice, this is removed from gender… but as viewers now, in a world which very much still has issues with gender inequality, these make for complex women with strong and uncompromising characterisation. They are allowed to make decisions which affect the plot as well as their own emotional state and relationships.
Self sacrifice is unfortunately a common theme in the post-apocalytic world where survival becomes the biggest objective. This hard decision mostly done by characters in 2 types of situations. The first one is being depressed and disappointed in the future when you are tired of constant fighting for survival. Characters just out of options to continue their way to the better world when they realize that there won't be one. And the second is made mostly by selfless people. It's a sacrifice for somewhat or someone. This happens when characters understand that giving up their life is the only option for someone else to survive or to prevent something even worse from happening.
|Charlotte||After killing Wells and seeing Murphy being punished for her actions, she jumped off a cliff.|
|Section 17 volunteers||Sacrificed themselves to provide The Ark more oxygen for their fellow residents' survival.|
|Finn Collins||Surrendered himself to the Grounders after being accused of murder to prevent a bigger conflict with the Sky People.|
|Chris||Killed himself after watching how his project - A.L.I.E. destroyed the world.|
|John Murphy||Tried to shoot himself after being locked in lighthouse bunker, but gives up.|
|Lincoln||He had an opportunity to escape with his friends but decided to stay and be executed instead leaving with his people.|
|Titus||Suffering from Lexa's death, prevented being used as a hostage for an unrightful commander.|
|Octavia Blake||Tried to kill herself with black rain, due to the loss of Lincoln, but Ilian stops her.|
|Jasper Jordan and his followers||Jasper himself was broken and fell into depression after losing Maya but, hearing about another end of the world, he lost his desire to live completely and gathered a group to end their torment and overdose themselves.|
|Raven Reyes||She was willing die in space and be happy but changed her mind because of her friends.|
|Charmaine Diyoza||Attempted to commit suicide by slashing her own throat to avoid being arrested, but survived.|
|Cillian||He was willing to die to stop the Primes from having another host. He initially was going to sacrifice his life to save Clarke, but failed after she tried to escape and he slit is own throat.|
|Joaquin||Blames himself for Rose's death and allows the plants and trees to consume him.|
|Dave||Becomes emotionally depressed when he believes that Josephine ignored him and broke up with him. He shot himself in the head.|
|Marcus Kane||Floated himself into space rather than live in another man's body.|
Notes and Trivia
- After Nevermore episode, Stephen King was inspired to tweet about the show. Sparking a mini-debate with William Shatner over twitter on morality in Arkadia.
- ↑ 1.0 1.1 ‘The 100' has facilitated important conversations about free will and rape culture, Hypable, April 12, 2016
- ↑ 2.0 2.1 Stephen King and William Shatner debate morality in ‘The 100’ season 3, Hypable, April 18, 2016
- ↑ 3.0 3.1 Violence and Morality in ‘The 100', Bitch Flicks, October 26, 2015
- ↑ 4.0 4.1 23 times 'the 100' made 'game of thrones' look like a lighthearted fantasy, MTV, July 29, 2015
- ↑ The 100 is back, along with its dirty faces and complex morality, avclub, Jan 21, 2016
- ↑ https://www.hypable.com/the-100-season-6-nycc-2018-first-look-spoilers/
- ↑ 7.0 7.1 season 3: trauma, free-will and perverse instantiation, DenOfGeek, 26 May 2016
- ↑ How the CW’s ‘The 100’ Is Getting Sex Positivity Right, Bitch Flicks, September 24, 2015
- ↑ TV and Classic Literature: Is ‘The 100' like ‘Lord of the Flies'?, Bitch Flicks, October 27, 2015
- ↑ King, Stephen (16 Apr 2016) Tweet “The sad (but true) mantra that's repeated over and over in THE 100: "There are no good guys."” - @StephenKing
- ↑ King, Stephen (16 Apr 2016) Tweet “What I like best about THE 100 is the strong feminist slant. No preaching, just story.” - @StephenKing
- ↑ Season 3: William Shatner and Stephen King debate morality in Arkadia, Melty