Eriana-3

Eriana-3 was a member of the ill-fated fireteam led by Eris Morn tasked with the assassination of Crota. She and everyone else in the fireteam died, leaving Eris as the only survivor. Eriana was also a Praxic Warlock and the owner of Eriana's Vow.

Biography
Eriana-3 was present during the initial attempt by Guardians to retake the Moon from the Hive. Knowing that the battle was going poorly, she captured and interrogated a Wizard, thus learning of Crota's existence. However, it would not reveal how to kill its master, much to her anger. It then showed her the death of Wei Ning and several other Guardians, further infuriating her.

In a moment of haste, she ordered all Guardians in the area to mount their Sparrows and ride to Mare Imbrium in hopes of turning the tide of the battle. After that particular battle ended in disaster, she went to a bar and stated how quiet it was without Wei's laugh. Eriana and Eris Morn decided to seek out Toland, The Shattered, seeking advice on how to kill Crota. Toland was recruited into their fireteam, along with the Hunters Omar Agah and Sai Mota, and the Titan Vell Tarlowe.

Wei Ning
Eriana was in a romantic relationship with the Titan Wei Ning; they were introduced by the Hunter Pahanin in the Tower saloon. Wei's death is what sparked Eriana's quest for vengeance against Crota.

Quotes

 * "I'll be the last Light they ever see."
 * "I vowed to avenge them all, and this curse I will carry to my final death."
 * "I'll find peace when I rip that monster's beating heart from his chest."
 * "Wei... I will see you again. But first… I have work to do."