River Song is the daughter of Amy Pond and Rory Williams, companions of the Eleventh Doctor. In some time between the Ponds' wedding at the end of the fifth series and the beginning of the sixth, a pregnant Amy was taken captive by the Silence, a religious order that wants to see the Doctor dead because of their belief that 'Silence will fall when the Question is asked', and kept in confinement until River (called Melody at this time) was born. A clone of Amy accompanied her husband and the Doctor on their travels during the first half of the sixth series.
The infant Melody is taken from her parents despite a rescue attempt, and raised in an abandoned orphanage and trained to kill the Doctor. As a young child, Melody discovers that she can regenerate like a Time Lord after her mother inadvertently shoots her. The second Melody, now Mels, goes back to her parents' childhood and grows up with them as their best friend, actually becoming pivotal in the development of her parents' relationship (turns out her parents would eventually name their daughter after this childhood friend, so she basically named herself. Never apply logic to Who). It was during this regeneration that Mels exhibited a dislike for rules, which carried over into her third regeneration, after Hitler accidentally shoots her. Mels thus becomes River Song, and poisons the Doctor with her lipstick. She later on heals him by using up her remaining regenerations.
River Song goes on to study archaeology, eventually becoming a professor. However, her past still catches up to her. The Silence force her to kill the Doctor on the shores of Lake Silencio in Utah. She tries to subvert this fixed point in time, and nearly causes time to collapse. The Doctor has to marry her in order to get her to set the timeline straight once more. River therefore goes to prison for killing the Doctor, although she is later pardoned because the Doctor, having faked his death, erased all hints of his existence from the universe.
River and the Doctor have a relationship told out of order, a relationship that they keep track of using blue TARDIS-shaped diaries. At some point in time, during the 2015 Christmas special, they go to visit the singing towers of Darillium, where the Doctor gives her a screwdriver. Soon after that, River goes to the Library, meets the Tenth Doctor, and dies — but the Doctor saves her one last time by uploading her into a virtual reality stored in the Library's central computer.
Considering her story, River could quite easily become a Canon!Sue. She is often paired with the Eleventh Doctor, if not being shunted to the side to make way for Mary Sue. She has also been known to mother Mary Sues.
River and the PPCEdit
In the interlude 'Plotholes and Meatloaf and Angels, Oh My!', the Doctor reveals that he recorded a meeting with some PPC agents who took him and River to FicPsych. Agent Morgan uses that unknown mission to show the Doctor how terrible Suvian possession is.