Riven of a Thousand Voices is a powerful Ahamkara that formerly served Mara Sov within the Dreaming City, before being Taken by Oryx, the Taken King. She now corrupts the city from its heart, the Keep of Voices, and worked her way into Uldren Sov's mind like a parasite, bending his will in an attempt to unseal the Dreaming City and free her. She is the true main antagonist of Forsaken, and the final boss of the Last Wish raid. After Oryx's defeat at the hands of Guardians, she served Savathûn, the Witch-Queen.
Accompanying the Queen
Riven was young during the earliest days of the Reef. When she encountered Uldren Sov, who was on a mission to find a power that would allow Mara Sov to build an impregnable Awoken city, she was drawn to his unfulfilled ambitions and allowed him to present her to Mara Sov. The Ahamkara took the name Riven, in honor of her host.   Through the years, she grew and accompanied Mara Sov in her ventures, becoming one of the most significant members of her entourage. Riven's wish-granting faculty played a key role in the construction of the Dreaming City. However, Mara remained wary of Riven's fundamental untrustworthiness and appetite as an Ahamkara. Mara constructed a Wall of Wishes to make bargaining with Riven safer, and made sure to keep her away from Uldren and other potential sources of trouble. Indeed, Riven's work on the Dreaming City included small but deliberate flaws that would make it vulnerable to attack.
After the Dreaming City was finished, Mara wished Riven trapped inside the keep at the heart of the city. She remained there for the rest of her life, though the Queen visited her regularly to make bargains.
Taken by the King
Shortly after the Battle of Saturn, the Darkness from Oryx's Dreadnaught Took the Techeuns from the battle, and the Taken invaded the Dreaming City, which was inadvertently revealed, in mass. At the Keep where Riven was kept, Oryx offered to Take Riven away, although she knew that Oryx would not let her leave the Dreaming City. Nonetheless, Riven, eager to try bargaining with a king, told Oryx to take whatever he wished, as long as if he 'wished' it. Riven and Oryx both knew they were attempting to deceive each other and began laughing together at the irony of their scenario. Following this, Riven's identity seemed to merge with Oryx's will, being simultaneously the Taken King and Riven. When Oryx was defeated by The Guardian, Riven felt the Taken King's despair at not being able to avenge his son Crota. Although her will was partly restored, Riven reflected that she was still trapped within the Dreaming City and could not escape, while also having no one within the City to talk to as the Techeuns, despite also being Taken, did not have free will like she did 
A New Master
Years after Oryx's defeat, Savathûn, the Witch-Queen infiltrated the Dreaming City and revealed herself to Riven. Without a Taken King, the Taken Riven was directionless, and asked Savathûn to "take up those strings." After this was done, Riven's Taken directive changed again. She became capable of exerting her influence outside the Dreaming City, and through her bond with Savathûn caught a glimpse into her plans. What Riven saw unsettled her.
At this point, Riven made contact with Uldren at the Tangled Shore, taking advantage of his overwhelming desire to hear from Mara again. She granted his wish by masquerading as Mara in his thoughts, and in that guise began manipulating him into eventually freeing her from the Dreaming City. Her influence also quickened the infection of Darkness within him.
Riven is ultimately responsible for the creation of the Scorn: when Uldren wished he had the power to save the mortally wounded Fikrul, Riven granted his wish by transmitting some of the Darkness in his body into the Archon's Ether, transmuting it into Dark Ether and reanimating Fikrul as the first Scorn.
Ultimately, thanks to the actions of Uldren Sov, the way into the Dreaming City became unsealed, allowing Riven the chance to unleash a Taken Chimera to devour Uldren. Though the Guardians and Reef agents ended Uldren and destroyed Riven's agent, the Voice of Riven, Riven herself remained a threat that the Awoken knew had to be dealt with immediately, especially since she was now Taken. Pleading the Vanguard and Guardians for aid, the Awoken succeed in gaining the support they need to launch an assault upon the heart of the corrupted Dreaming City and end the Taken Ahamkara.
A Guardian Raid team was formed and breaching into the Keep of Voices at the heart of the city, the Guardians battle two of the Taken-corrupted Techeuns: Kalli and Shuro Chi. Not only were they successful in defeating the Taken Techeuns but were able to actually free them from the Taken's influence. Gaining their aid, the Guardians finally confront and battle with Riven. The battle takes them between the physical and Ascendant planes but they were able to mortally wound Riven. Ensuring that the Ahamkara never becomes a threat again, the Guardians enter the Ahamkara herself and destroyed the Blight surrounding her heart, taking the relic back to the Queen's Techeuns to finish cleansing it of the Taken corruption.
This was, however, exactly what Riven wanted. As an Ahamkara, Riven was able transcend death in order to grant one last wish made by the Guardians' collective wish to save the city: Altering the rules of ascendancy within the Dreaming City as the realm became cursed partially into the Ascendant Plane and trapped in a three-week time loop actualized by the Taken Quria, Blade Transform. Even after death, Riven was freed from her prison and her soul became tied to her killers as her Siren would continue to whisper at them, specifically when they reach Mara Sov's former throne world, Eleusinia.
As an Ahamkara, Riven is calculating and fundamentally self-interested. She is extremely adept at wish-magic, having been the architect of the Dreaming City itself. She enjoys riddles and bargains, and has no issue manipulating the wishes and desires of others to serve herself, even those of the Queen, who was her confidant for centuries. Riven is more placid than most Ahamkara, however, and initially stayed with the Awoken despite the rich hunting in the inner system because she enjoyed basking in the "heat" of Mara's self-realization.
Riven is capable of mimicking the voices of others, perhaps earning her epithet "Of A Thousand Voices". During her corruption of Uldren, after being Taken, she showed the ability to invade his thoughts and project the image of Mara into his surroundings.
Like the rest of her kind, Riven is a shapeshifter, and typically adopts reptilian or dragon-like forms. After becoming Taken and corrupting the Dreaming City, she confronted the Guardian as a gigantic clawed and tentacled serpentine beast, with a head covered in numerous eyes, protected by folding bone plates that act as secondary jaws.
Riven has retained her free will even after being Taken. At one point, she held complete dominion over the Taken in the Dreaming City, with powerful Taken such as Morgeth and the Taken Techeun witches at her command.
List of appearances