The commander of the allied Grounder clans, Lexa is proven to be a reasonable leader and strong warrior.She considers love a weakness, a view significantly impacted by the death of her girlfriend, Costia.
After a group of survivors find the communications tower, they are forced to split and take shelter from an acid fog.
In "Long Into an Abyss," with the Grounders' deadline imminent, Abby (Clarke's mother) and Jaha disagree over what the survivors are to do; Jaha wishes to evacuate to the so-called 'City of Light', while Abby wants to remain behind to rescue other members.
Clarke and two of her fellow people (Octavia and Bellamy) hold Lincoln in the dropship; he is a Grounder and was experimented on with a serum to become a reaper (a mindless, zombie-like killer).
When Lincoln is almost mercy-killed, his heart stops and he is revived by Clarke, who believes curing reapers depends on waiting for the serum to leave their bodies, even though the reaper might temporarily die in the process.
With this information, Clarke realizes they have something to offer the Grounders.