She is usually presented as an advisor, quest-giver and item vendor within the Destiny series, although she has occasionally played a proactive role to assist the Guardians, protectors of Earth's last safe city.
Eris Morn has been subject to merchandise and promotional material, and is noted by commentators as one of the most prominent characters of the Destiny series' and an important aspect of its lore.
Several Bungie team members elaborated the direction and tone of the series in detail for audition hopefuls in order to illustrate their vision for who they wanted Eris to be.
[3] To prepare for the role, Gorrondona drew from her experience working in professional theatre to develop the minute details of her personality, as well as her training in improv techniques which allowed her to "make decisive but not obvious choices within seconds".
[1] She described Eris' early appearances in expansion content for the first Destiny as "slowly slipping into madness after her time spent with the Hive", and that is due to her inner conflict because she has an "odd reverence" for her tormentors that is only matched by her desire to see them destroyed.
[3] For her subsequent major appearance in Destiny 2: Shadowkeep, Eris is literally haunted by the ghosts of people from her past, which are manifested by a mysterious structure introduced in the expansion.
[1] From her perspective, Eris is also indicative of an emerging cultural shift within the video game industry in terms of the representation of women and how female characters are portrayed in the medium.
Taking advantage of an internal struggle within the Hive faction, she directs the Guardians to destroy Crota’s crystal and kill his partner, the witch Omnigul.
Eris warns the Guardian Vanguard leadership at the Tower about the threat posed by Oryx's Taken, a faction which consists of ghostly-looking corrupted versions of regular enemies.
Eris reappears in Shadowkeep, where she discovers a giant Pyramid ship buried under the surface of Earth's moon, and finds herself haunted by the ghosts of her old fireteam after she accidentally activates the structure.
She assists her allies in defeating Nightmares, which are manifestations of Darkness energy manipulated by the Moon’s Hive presence that take on the appearance of the Guardians' major enemies from the past.
Her knowledge would be used well as her and the Guardian were able to sever Calus's connection to the Lunar Pyramid by transforming the Nightmares tormenting their allies into Memories, though they were too late to prevent his ascension into a Disciple.
That enemy was revealed to be Ahsa, a proto-Worm God who held information on the origins of the Witness, its pursuit of the final shape, and the next step to follow it into the portal.
After the Coalition rescued Ahsa at the end of Season of the Deep, she revealed that Savathûn must be brought back in order to get the solution they need to follow the Witness.
Eris eventually ascended into the Hive God of Vengeance through a ritual and tasked the Guardian with collecting the tribute she needed to challenge Xivu Arath, uncovering the Deck of Whispers in the process.