Evelyn Johnson-Eaton is Tobias's mother and the leader of the Factionless. She was responsible for the idea of destroying the Dauntless so that Jeanine Matthews would lose control of the government, but deceived the Dauntless into believing that their goal was to restore the peace of the old faction system, when her true goal was to abolish all of the factions.
Evelyn is described as being middle-aged with curly black hair, olive skin, stern/angular features, hooked nose, strong jaw, spare upper lip, stick-out ears, and dark eyes that look almost black. In the books she is of Hispanic descent.
At one point, she met Marcus Eaton, married him and had Tobias with him. Due to Marcus' abusive nature, he often beat Evelyn. Eventually, Evelyn had an affair and left them, after Marcus attempted to exile her from Abnegation. She then faked her death, believing that their son would be safer with Marcus, despite the fact that he also abused Tobias.
A year after Tobias transferred to Dauntless, she sent him a coded message to meet him at the train yard and, according to Tobias, it wasn't a happy reunion.
Evelyn meets Tobias, Tris Prior, Caleb Prior and Peter Hayes at the Factionless headquarters and convinces Tobias to become a Dauntless leader in order to ally with the Factionless. After the alliance defeats the Erudite and the traitor Dauntless, the Factionless take control of all the weapons before Tobias plays the video.
Tobias believes his mother while Tris does not.
Evelyn is against the Allegiant group which Tobias and Tris are in, but she doesn't know. So, the Allegiant escape the city and go to the Bureau of Genetic Welfare and after a while, Evelyn disappears of the story. She appears again when Tobias watches her sentence Marcus (who is under the Truth Serum) to leave Chicago and never come back. But, Marcus hid near the Hancock building and later on he meets with Johanna Reyes and they create The Allegiant group that stayed in Chicago even bigger and later on attack Evelyn's band of Factionless. Evelyn finds The Death Serum in Erudite Headquarters and keeps it. After that, the Bureau decides to Reset the city, but the Allegiant in the compound go save the people they don't want to be reset. Tobias decides to reset his mother instead of his father. However, he gives Evelyn the choice to call up a treaty with Marcus and Johanna and start over as Tobias' mother like she was supposed from the beginning. She chooses to be a better mother and call up the treaty.
Evelyn married Marcus and conceived Tobias. Later on in the relationship, Marcus showed his abusive nature and started beating Evelyn which led her to having an affair and leaving Tobias and her husband.
Evelyn is Tobias's mother. They have a difficult relationship due to the fact Evelyn left Abnegation, leaving Tobias at the mercy of his abusive father.
In the events of Insurgent, Evelyn appears to reunite with her son but is later revealed to have used him to gain control of the Dauntless.
In Allegiant however, when Tobias gives her the choice of continuing with the battle against the Allegiant or having her son back, she chooses her son, divulging that she truly loves Tobias.
Evelyn shows disdain for Tris saying "I am his family. I am permanent. You are only temporary." Tris does not trust her and eventually learns of Evelyn's true plans for the city.