Sloane served in the Alliance, participating in the Skyllian Blitz, but was discharged after punching a superior officer for "bureaucratic bullshit." Although some of the Initiative's senior leadership had concerns about Sloane's temper, Jien Garson was impressed by her passion, frank attitude, and resourcefulness. Sloane Kelly was later employed by the Andromeda Initiative as head of Nexus security. During the Nexus uprising, Sloane and the new Initiative Director, Jarun Tann, had a falling out. Sloane sympathized with the rebellion and was vehemently against using the krogan against the mutineers; thus Sloane took it personally when the Director went behind her back to make a deal with Clan Nakmor in order to violently put down the insurgents. Upon learning of the Director's intervention, Sloane switched sides and joined the rebellion. The rebellion failed however and she was exiled to Kadara along with the other mutineers. While on Kadara, Sloane amassed a group of followers from the exiles called the Outcasts and drove out the local kett forces from Kadara Port. Ever since then, the Outcasts became the ruling power in Kadara and began raiding the Nexus' convoys, transports, and scout teams for supplies and equipment.
While attempting to locate the Archon's flagship, Pathfinder Ryder meets with her, hoping to secure the release of angaran Resistance traitor Vehn Terev. Regardless of the way the discussion goes, Sloane refuses to release him.
Sloane's authority over Kadara Port has been called into question by many of its inhabitants, and by the time Ryder arrives, a new faction known as the Collective has already emerged to disrupt her operations and overthrow her.
Eventually, Sloane is contacted by the Charlatan, the Collective's leader, and is challenged to a one-on-one fight. If Ryder is enlisted as her back-up, they can choose to either save her or leave her to die.
Should Ryder choose to save Sloane, the Charlatan will be forced to flee and the Outcasts' rule on Kadara Port will be reinforced. She will allow the Initiative to settle an Outpost on Kadara for the sake of the Pathfinder, stating that while she will never trust the Initiative, Ryder is "out of the doghouse", on the condition that the outpost pays a regular protection fee. Later on she assists Ryder in the final battle for Meridian against the Archon.