President Alma Coin was the president of District 13 and the leader of the Second Rebellion against the Capitol. While President Snow is still the antagonist of the series, she is the hidden but true main antagonist of Mockingjay.
Coin was first introduced when Katniss Everdeen met her in District 13. Although initially appearing to fully support the rebellion — and demonstrating considerable leadership abilities — Katniss later realized that for Coin the war was a means to an end; pitting the Capitol and the districts against each other to clear her own path to power, and she was willing to sacrifice almost anything or anyone to achieve her goals, including Katniss herself. After Katniss' sister Prim was killed in a bomb drop orchestrated by Coin, Katniss showed up at Snow's execution, seemingly to kill him, but shot and killed Coin instead.
Virtually nothing is known about Coin's early life. She was presumably raised in District 13, eventually rising to become its president. In the film Mockingjay - Part 1, Prim mentions to Katniss that Coin lost her husband and daughter during the smallpox epidemic that broke out in the district years earlier. Her cold, controlled nature may be due, at least in part, to the loss of her family.
Due to Katniss Everdeen's unique position as a symbol of rebellion to the districts, Coin had Katniss, along with Finnick Odair and Beetee, rescued from the arena following the 75th Hunger Games, after Katniss had destroyed the force field surrounding the arena. However, she was not able to rescue Peeta Mellark, Johanna Mason, and Enobaria. With Katniss safe in District 13, Coin was forced to cooperate as Katniss recovered from her physical and mental traumas, although Coin was rather impatient: Like the other rebels, she needed Katniss to don the label of Mockingjay, and help fuel the districts into rebellion.
After orchestrating many propaganda films staring Katniss and other members of the rebellion, the tide began to turn in the rebellion's favor. After Peeta attacked Katniss which added fuel to Katniss's fire, Coin presumably started to see her as a threat to her power. However, they remained allies due to the fact Katniss was the face of the rebellion.
After Katniss recuperated, she snuck into the Capitol without Coin's knowledge. When Coin found out, she remarked that Katniss was hard to control. During the mission, Boggs told Katniss that Coin may view her as a threat, which Katniss thought ridiculous. After Boggs' death, she tells the others that she has been sent by Coin on a mission to kill Snow in an attempt to make them cooperate with her. When she later reveals that there was no mission set by Coin, they tell her that they already knew but followed because they believed in her.
During the invasion of the Capitol, Coin managed to contact Snow by intercepting one of his broadcasts when Katniss and the team were thought to have died. She makes a speech about Katniss and her bravery, but it's likely Coin was doing this to back the rebellion and also because she no longer saw Katniss as a threat.
After President Snow's capture, Coin assumes the post of interim President of Panem, claiming it is not the right time to hold elections yet; she later brings the seven remaining victors for a meeting in the President's mansion on whether they should hold one last Hunger Games with the Capitol's children. Johanna and Enobaria vote yes, whereas Peeta, Annie and Beetee vote no. Katniss votes yes in order to gain Coin's trust and asks if she can kill Snow, to which Coin agrees. Haymitch then sides with Katniss. However, prior to this Katniss attributed Prim's death to bombs dropped by President Snow, however when she goes to visit him, he tells her that it was Coin who dropped the bombs, as he wouldn't have any reason to kill innocent civilians of the Capitol, saying "Anyone could see that the game was over by that point."
During the execution of President Snow, Katniss remembered the conversation she had with Snow and realized President Coin was behind Primrose Everdeen's death, along with the death of a great number of rebel medics. So instead of shooting Snow, she turned her single arrow from Snow to President Coin and shot her instead, partly to avenge Prim's death. President Coin fell off the balcony as the people looked on in fear and horror. It is possible that she didn't die from the arrow, but from the fall itself. This resulted in Katniss being taken away and declared mentally unstable. President Snow also died, although whether it was from coughing up blood from "the many mouth sores that will never heal" or from being trampled by the ensuing riot was unknown. Besides the desire to avenge her sister, Katniss recognized that Coin, now in control of Panem, would simply take the exact same road as Snow to keep her position.
When Katniss first began to fight the Capitol, President Coin's stance was to end the Hunger Games and there would never be another one, securing Katniss' support. However, after defeating the Capitol, Coin asks the remaining victors about using Capitol children for one last Hunger Games, intended to appease the District citizens rather than exterminate most of the Capitol population. Realizing that this may have been the same kind of justification used by the Capitol used when they created the Hunger Games seventy-five years earlier, Katniss recognizes that the Games are unlikely to end when Coin comes to power, leading her to also use this reason to kill President Coin.
"She's fifty or so, with gray hair that falls in an unbroken sheet to her shoulders. I [Katniss] am somewhat fascinated by her hair since it's so uniform, so without a flaw, a wisp, even a split end. Her eyes are gray, but not like those of people from the Seam. They're very pale as if almost all of the color has been sucked away. The color of slush that you wish would melt away."
President Coin was described as being about 50 years old. She had perfect grey hair - so perfect it fascinated Katniss " as it was so uniform, so without a flaw, so wisp, even a split end " that Katniss wonder if it was a wig - that fell in an unbroken sheet to her shoulders. Her eyes were also grey, but not in the same way that many of the mining families of District 12 had grey eyes, they were so pale that Katniss described them as looking like "all the color was sucked away" and "slush that you wish would melt away".
Not much is known about President Coin initially, and her highly restrained emotional state rarely showed any cracks, giving no obvious indicators of her true personality or motivations. However, Katniss eventually realizes how power-hungry Coin is, and how far she will go to achieve her goals. It is not clear if she ever truly sympathized with the people of Panem, although growing up in District 13 she certainly shared in any hardships that blighted the district, hardships that were indirectly the result of the Capitol's tyranny. Katniss mentions that she "certainly doesn't have the sole claim against Snow's life...", and that she can count on Coin "...getting the job done.", indicating that Coin may also have personal motivations for bringing President Snow down. Coin certainly proved herself a more capable leader than Snow: She managed her large, complex, and militarized district with extraordinary efficiency; did not immediately resort to repression at the slightest infraction; and was flexible enough to realize that her way of doing things was not always the most effective.
However, Coin was narcissistic, callous, patient, arrogant, cynical and charismatic to the extreme. She was deceptively intelligent, to the point of arrogance, and was able to outthink President Snow himself, who didn't realize her plan until it was already in action. She possessed extraordinary degrees of Machiavellianism, in that she was flawlessly able to influence the whole of Panem into civil war so that President Snow eventually dies, allowing her to become president of Panem.
She makes it clear that she views Katniss as an inferior and a mere icon for the rebellion, and is miffed when Katniss makes demands, and is forced to go along with them in the face of the public.
Even so, Coin viewed Katniss as an eventual threat, and meant to have her die and become a martyr, inspiring the rebellion with Katniss' supposed "sacrifice". This would have aided her in her plans in that she would be rid of Katniss, who was too independent and selfless to control, and she would be able to take charge of the rebellion without Katniss' intervention. Nevertheless, President Coin possessed a massive amount of patience, in that she was prepared to wait years before she was in a position to seize power in Panem.
In the end, after the rebellion is victorious, Coin attempts to secure the remaining victors' loyalty with the proposal of a final Hunger Games, using the children of the Capitol higher-ups, and in her arrogance she believed herself to have secured Katniss' loyalty. This shows that her self-obsession and narcissism knows no limits, but on the other hand it proves to be her undoing: Now that Snow is finally at her mercy, she becomes overconfident and unaware that Prim's death has traumatized Katniss against Coin, especially when it is discovered that Coin was the one who had Prim murdered. She saw no hesitation in executing President Snow, since Snow's death would finally grant her absolute, unlimited power.
However, Katniss eventually realized that it was Coin who authorized the bombing of Capitol refugees and their children, as well as her own medic corp during the conclusion of the invasion, which resulted in the deaths of many men, women, and children that included Katniss' sister, Prim. As a result of this realization, Katniss executed Coin with her single arrow instead of President Snow, ending a much more dangerous threat before it had a chance to begin. It can be speculated that the key difference between Coin and her enemy Snow is that Snow was far more careful with the power he obtains than she was - she overplayed her hand, and the consequences destroyed her.
- In the film The Hunger Games: Mockingjay - Part 2, Boggs mentions that Coin doesn't like anything she can't control, noting her dislike for Katniss, some districts, and likely other individuals as well.