Sloane, the Titan Vanguard representative on Titan, was last seen fighting off the Hive during the events of the “Season of Arrivals” in Destiny 2. She chose to stay behind and defend the arcology as the Darkness approached, and her ultimate fate is left ambiguous.
In the “Season of Arrivals,” which preceded the “Beyond Light” expansion, the Pyramids—ships of the Darkness—began appearing throughout the solar system, including near Saturn’s moon, Titan. As these Pyramids started to exert their influence, the Vanguard made the decision to evacuate key personnel from various locations. Sloane, who had been the de facto leader of the human outpost on Titan since the Red War, refused to leave her post despite the impending threat.
During the evacuation, players could visit Sloane to receive a final message and see her donning a full suit of heavy, Hive-themed armor, preparing to make a last stand against the encroaching Hive forces. This was a part of the “Exodus” questline, where players assisted various characters in preparing for the evacuation.
Sloane’s decision to remain was in line with her character as a steadfast and loyal defender of humanity. She was determined to protect the arcology to the very end, even if it meant facing overwhelming odds. The game does not explicitly show her death, leaving her fate somewhat open to interpretation, but the strong implication is that she likely perished in the battle, making a heroic last stand against the Darkness.
As of the current state of the game, Sloane has not reappeared, and the Titan location itself was vaulted—removed from the game—when the “Beyond Light” expansion was released. This has led players to speculate about her ultimate fate, but as of now, no further information has been provided by Bungie, the developers of Destiny 2.