Sydney is an independent mercenary who specializes in obtaining relics. She prefers going for the more dangerous scores (like the Declaration of Independence) and takes risks. She is beautiful, but finds men approaching her irritating. She is a loner. She prefers not speaking about her dark past. When she was very young, her mother was raped and killed by raiders. She spent years perfecting her combat skills and never welshes on a deal.
As a child, Sydney was orphaned when her father was killed during a weapons trade off at the Statesman Hotel. She had to wander D.C. alone, but she was able to handle herself because her father had taught her how to handle and maintain guns, and to upgrade them since she was young. Sydney then became a relic hunter and did some work for Abraham Washington. In her own words: "After he loaded me up with caps, I got piss drunk, got laid, and was happy for the first time in a while. I haven't looked back since."
A note from Little Moonbeam's father is a note Sydney's father left her when he was dying in the Statesman Hotel. If you give it to her after she tells you her story, she will give you Sydney's 10mm "Ultra" SMG.(This process can be repeated as many times as one likes. Simply reselecting the conversation option about Sydney's father gives the PC access to an infinite supply of Sydney's 10mm "Ultra" SMGs.)
If Sydney remains alive at the end of the quest, she will travel from Rivet City to the Ninth Circle in Underworld and set up shop as a vendor, stating that she likes to hang out at Underworld because the ghouls do not constantly hit on her.
If you enter combat with the residents of Underworld while Sydney is a vendor there, she will fight on your side, unless you intentionally (or accidentally) attack her.
She can be very helpful in exploring the ruins of D.C. at lower levels, especially when used in conjunction with other companions such as Dogmeat and Charon due to their lack of a Karma requirement. However, it is advisable to carry a sizable supply of stimpaks to keep her healed through dialog, and to watch her health carefully, as unlike a permanent companion she does not automatically regenerate health.
It is possible to pickpocket and reverse-pickpocket Sydney for items, after the super mutant attack, but before speaking to her. However, once you recruit her as a companion, pickpocketing, or reverse-pickpocketing her is not possible until Stealing Independence is concluded with Sydney surviving. Also, if you decide to give her a different weapon other than Sydney's 10mm "Ultra" SMG, she will use up any ammunition you give her.
pcps3xbox360 There is an exploit that makes it possible to receive an unlimited supply of Sydney's 10mm "Ultra" SMG in perfect condition and 10mm ammunition. It can be found under the Sydney's 10mm "Ultra" SMG article. [verified]
pcps3xbox360 You can't pickpocket Sydney after recruiting her - neither during the quest nor after completing it. You just get the "talk" option when crouching. [verified]
xbox360 When she's in the bar in Underworld, she can sometimes die and will be slumped over the floor. It is unknown what causes this. [verified]