Melody Pond

Professor River Song was a mysterious archaeologist and convicted murderer who shared a close relationship with the Doctor. Significantly, she was the only companion who appeared to know the Doctor's true name.

Although his first meeting with her ended in her death, they had many adventures — from the Doctor's perspective — afterward. Like Melanie Bush before her, she was an example of the rare companion whose timeline was not synchronous with that of the Doctor.

Early Life
River Song was an archaeologist already highly familiar with the Doctor when they first meet (from his perspective) in the 51st century. She was, in fact, a future companion of his who travelled with him off and on. According to her, he came to trust her implicitly, though at the start of their relationship (from his perspective) he was generally suspicious of her and almost hostile to her at times. Prior to her encounter with the Weeping Angels, she was imprisoned for murder of someone she described as, "A very good man. Best man I've ever known." She was imprisoned in the Storm Cage Facility until she was put under Father Octavian's custody. If she were to carry out the mission assigned to her she would earn her pardon. (DW: The Time of Angels / Flesh and Stone)

Opening of the Pandorica
After escaping from prison, River made a deal at a black market for a Vortex manipulator that she would use to travel back in time to the Roman era of Earth and pose as Cleopatra. (DW: The Pandorica Opens)

Crash of the Byzantium
Doctor River Song was a guest on the Byzantium ship in the 51st century. She was working for a military organisation at the time in exchange for the pardon of a murder. She infiltrated the lower levels to find the Home Box, into which she carved the message "Hello Sweetie" in the Old High Gallifreyan language to attract the Doctor's attention. About 12,000 years later the Doctor found the Home Box in a museum. The Doctor used the cube to see who wrote the message. Seeing her being pursued by guards and giving him the co-ordinates of her location, he went to rescue her. She then jettisoned herself from an air lock, where the waiting Doctor and Amy Pond picked her up in the TARDIS. River then showed exceptional TARDIS flying skills landing it next to the Byzantium, which had crashed into the Maze of the Dead. Along with the Bishop and his Clerics, River accompanied the Doctor and Amy into the maze. She made it out of the maze alive along with Amy and the Doctor, to be imprisoned once more, but she thought she may have done enough to earn a pardon. She then mentioned to the Doctor about their meeting at the Pandorica. (DW: Flesh and Stone)

Death
River's expedition to the Library was financed by Felman Lux and was chartered to discover what disaster had happened there, years previously, that had caused 4022 people to "die" or disappear. When her team ran into trouble during the expedition, River summoned the Doctor by sending him a message via psychic paper. The version of the Doctor who turned up had not yet met her. Though bewildered, he agreed to help River and her team. River and the Doctor appeared to be very close, even considering the strong bonds the Doctor forms with his companions. She kept a worn and battered diary, the cover looking very much like the TARDIS doors, keeping a journal of her travels with the Doctor. There was a suggestion that in the Doctor's personal future he would carry a similar journal, as she commented about needing to "compare" diaries. She carried an upgraded version of the sonic screwdriver which "her" version of the Doctor had given her.

As the situation in the Library deteriorated, River realised she must prove to the Doctor that she was, or will become in his case, someone he trusted completely and with profuse apologies, she whispers his true name into his ear. The Doctor was stunned by this information, and River succeeded in winning his trustRiver physically died when she chose to sacrifice herself in order to stop the Doctor from sacrificing himself in order to save Donna and the other 4022 people trapped in the Library's computer. She pleaded with him to not try and change history, not to change one moment of what is to come for them. After saving all the trapped people, the Doctor realized his future self must have given her his sonic screwdriver for a reason. Inside he found a data chip, which contained River's Data Ghost. The Doctor saved her by uploading her into the virtual world contained in The Library's data core. CAL, the library's data core, controlled by a human girl wired into its mainframe, also managed to save the data ghosts of all of River's dead archaeological team, so she would have company in the virtual world. River would go on to take care of two virtual children in the virutal world, reading out her diary of her life with the Doctor and how "everybody lives" when the Doctor comes to call, her story ending with her telling the sleeping children sweet dreams. (DW: Silence in the Library/Forest of the Dead) The Doctor would later remember her death when Davros reminded him of the people who had died in his name. (DW: Journey's End)

Other information

 * River Song seemed to take shorter trips with the Doctor, living a more or less normal life between trips, rather than having one extended trip with the Doctor and never seeing him again after parting ways.
 * River Song is a skilled TARDIS pilot (with very different methods from the Doctor). She has mentioned that she "learned from the best" but implied that her teacher was not the Doctor.
 * Song appears to have knowledge of Time Lord anatomy, including knowledge of regeneration. She indicates that destruction of both of the Doctor's hearts is a circumstance after which regeneration is not possible.
 * River Song has the ability to write messages in High Gallifreyan.
 * River possessed pictures of all the Doctor's incarnations.
 * River is sentenced to prison for murdering a man described as "a hero of many" and whom she calls "A very good man. Best man I've ever known". Octavian felt that the murder victim's identity is something that the Doctor "really [doesn't] want to know."
 * Before his death, Octavian tells the Doctor that "You think you know [River], but you don't. You don't understand who or what she is."

River Song's timeline

 * Meets the Doctor for the first time.
 * Has an adventure with the Doctor at the Bone Meadows. (mentioned DW: The Time of Angels)
 * Has a picnic with the Doctor at Asgard. (mentioned DW: Silence in the Library)
 * Kills "a hero to many", "the best man [she's] ever known" and is imprisoned. (mentioned DW: Flesh and Stone)
 * Escapes from her Storm Cage (DW: The Pandorica Opens)
 * Meets the Doctor in 102 AD when the Pandorica Opens. (DW: The Pandorica Opens)
 * Father Octavian releases her from Storm Cage. (DW: Flesh and Stone)
 * Four days later, she breaches the Byzantium and is rescued by the Eleventh Doctor. (DW: The Time of Angels)
 * River Song and the Eleventh Doctor investigates the crash landing of the Byzantium. (DW: The Time of Angels)
 * Travels to the End of the Universe with the Doctor. (mentioned DW: Silence in the Library)
 * The Doctor, with a new haircut and a suit, visits River Song and takes her to see the Singing Towers of Darillium. He gives her his Sonic Screwdriver.
 * Tries to send 'her Doctor' a message via the Psychic paper, asking him to come to the Library. (DW: Silence in the Library)
 * The Tenth Doctor, whilst traveling with Donna Noble comes to the Library in the 51st Century at her request and meets River Song for the first time, when they face an infestation of Vashta Nerada within the Library.
 * Proves to the Tenth Doctor how important she will be to him by whispering his true name in his ear. (DW: Silence in the Library)
 * Sacrifices herself to save the Tenth Doctor and the Library. (DW: Forest of the Dead)
 * The Tenth Doctor beams River Song from a Neural Relay in her sonic screwdriver into the Library's Data Core. (DW: Forest of the Dead)
 * River Song's brainwaves live on in the virtual world inside the Data Core, containing CAL and Doctor Moon. She is reunited in this virtual world with her crew mates, Proper Dave, Other Dave, Anita and Miss Evangelista, whose brainwaves must have also been added to the Data Core. (DW: Forest of the Dead)

River mentioned a number of these events shortly before her death, raising the question of when any of the unseen events took place, and which incarnation of the Doctor (presumably between his eleventh and thirteenth) they coincide with.

''Some of the above events that have only been mentioned, may not have occured exactly where they have been placed here. For example, when River "travels to the end of the universe" with the Doctor, it may have been in her earlier or later life.''

Personality

 * It is unknown precisely where in time and space River Song originally came from. As the Doctor has left previous companions in different parts of the universe from where he originally found them, it is possible that River was not originally from the 51st century at all.
 * In a recent interview by Digital Spy, Steven Moffat made a passing comment to the effect that River Song might turn out to be very different from people's presumptions as to who she really is.