It is revealed through the course of the series that Sloane speaks Spanish, French, Japanese, Nepali, Mandarin, and Russian and reads Homeric Greek.

Sydney believes that she didn't meet Sloane until she was recruited, as she reveals in season 2 episode Cipher that she has "big gaps in [her] memory" around the time of the death of her mother.

Unable to bring himself to do this, Sloane set up an elaborate ruse, including the amputation of Emily's finger, to convince the Alliance that she was dead.

Concurrent with his engineering the downfall of The Alliance and SD-6, Sloane went underground, allying with Julian Sark and continuing his obsessive pursuit of Rambaldi artifacts.

They attempted to flee together, with cover fire from Julian Sark and the help of Sydney's mother, Irina Derevko, (who was stealing a Rambaldi book) to Sloan's awaiting helicopter, but Emily was accidentally shot in the shoulder by the bullet meant for her husband and killed by Marcus Dixon, a former SD-6 agent now with the CIA.

In retaliation, Sloane later arranged for Dixon's death by having a bomb placed in his vehicle one night while he and his wife, Diane, were having dinner with Sydney & Vaughn.

Between seasons 2 and 3 (the two-year gap where Sydney went missing), Sloane turned himself in to the U.S. government and, in exchange for a full pardon, utilized all of his knowledge to help bring down various terrorist organizations.

Sloane then moved to Zürich, Switzerland, setting up a humanitarian organization called Omnifam and apparently becoming a philanthropist, claiming that his research into Rambaldi's secrets led him to one word: peace.

Sloane still occasionally worked for the CIA by utilizing his contacts with the Covenant and other organizations, but his motives still elicited suspicion within the government, and particularly from Sydney, who never forgave him for authorizing the murder of her fiancé during the SD-6 days.

Sloane determined that The Passenger was his daughter with Irina Derevko, a woman named Nadia Santos who was an agent with Argentine intelligence.

Sloane is subsequently pardoned again and is recruited by the CIA to head up a new black ops division patterned after SD-6, called Authorized Personnel Only (APO).

"Arvin Clone" (real name Ned Bolger) is blamed for Irina's death by setting her up to appear as if she had contracted an assassin to kill Sydney.

Toward the conclusion of the fourth season, Sloane confesses that through his work with Omnifam, he has seeded water supplies around the world with chemical contaminants designed to make humanity more peaceful.

He abandons his post as APO director, apparently to join Elena Derevko's scheme to destroy civilization using the contaminated water in conjunction with the Mueller device.

During the final mission to stop Elena, Sloane aids APO, but in doing so is forced to shoot Nadia (who has been transformed by the chemical contaminants into a killing machine and is strangling Sydney).

Dean is captured by APO, but Sloane soon finds himself becoming beholden to another (as yet unexplained) element of Prophet Five, who holds the key to curing Nadia.

When Nadia casts Page 47 into the fireplace, Sloane's obsession takes hold and he throws her out of the way to save it, accidentally killing her when she falls through a glass table.

Sloane finally set about achieving his endgame, kidnapping Marshall Flinkman and Rachel Gibson to force them to hack into a satellite network to locate a cavern where he could utilize another Rambaldi artifact, an amulet, to uncover further details towards the fruition of his ultimate goal.

As Sloane's body collapsed, he fell into a vat of the strange liquid created by The Horizon which imbued with him special gifts, apparently the ultimate revelation of Rambaldi, immortality.