Sydney Bristow worked as a double agent for the CIA to take down SD-6 until she succeeded at that in season 2. She still works for the CIA helping to catch Sloane, who is now operating on his own.

Jack Bristow is Sydney's estranged father. He was a senior officer at SD-6 until it was destroyed. Even though he hasn't acted much like a father to Sydney in the past, he's now trying and has saved her life several times.

Irina Derevko, or Laura Brisow, is Sydney's mother. She worked for KGB and only married Jack to steal secrets. She killed many CIA agents and faked her own death when Sydney was just six. She was discovered to be "The Man" before she turned herself in to the CIA.

Michael Vaughn is a CIA agent who is assigned as Sydney's handler. He helped her take down SD-6 and now they are finally having the romantic relationship they have both been waiting for.

Sloane was the head of SD-6. He and Sark put together an elaborate plan to actually help Sydney and the CIA destroy SD-6. He now works with Sark to collect more Rambaldi artifacts.

Francie is Sydney's best friend and roommate. She has no idea what Sydney really does, she just believes that she works for a bank. In season 2 she opened her own restaurant and started a romance with Will. But soon a double killed her and is now pretending to be her and spying on Sydney for Sloane.

Will Tippin is one of Sydney's best friends. He worked as a reporter until his snooping led him to find out Sydney's secret. To save himself and Sydney from SD-6 he had to fake a heroin addiction, losing his job in the process. He now works at the CIA helping them with research. He has also started a relationship with Francie, not realizing that it is really an evil double of her.

Marcus Dixon is Sydney's missions partner at SD-6. Sydney kept the real identity of SD-6 a secret from him for 2 years. She then told him the truth right before they destroyed SD-6. He eventually forgave her and went to work with the CIA.