Siri was originally from a small town in New Mexico before the Legion burned it down. She has been a slave for the Legion for three years. Before her capture, she was receiving medical training to become a doctor, but was never able to finish it. Siri is the only adult female as well as adult slave in the Fort that is able to open dialogue.
If returning Melody's teddy bear, Siri will remark that it was a kind thing to do.
If the Courier are accepted by the Legion she will give a satchel of healing powder every day if asked, and six if they have helped her with her recipe.
If the Courier begins to kill members of the Legion, she will flee from her location and one will be unable to speak with her at all (she reverts to simply saying "Excuse me." like all the other slaves in the Fort).
If the Courier is female, she will comment about how long it was since she saw a free woman, and warn the Courier to look out since she overheard some legionaries whispering about "trying you out."
PC Siri may disappears from the game for no apparent reason. A possible fix for this bug may be to use the console commands prid 11fbbd, disable, enable, resurrect and moveto player, in that order. This will revive Siri and place her where you are, allowing you to talk to her.