When Abaddon begins her plans to build a demon army by stealing innocent people's souls, she, Agnes and two other demons possess nuns at St. Bonaventure Convent where they begin stealing the nuns' souls. Without souls, one of the nuns, Sister Mary Catherine goes on a rampage and kills two people before jumping from the convent's bell tower. Sister Mary Catherine's actions drew the attention of the Men of Letters; believing it to be a simple case of demonic possession, they send initiates Henry Winchester and Josie Sands to investigate in the guise of a priest and a nun from the Office of the Inquisition. The two meet with Agnes and Abaddon, who was possessing the Mother Superior of the convent and Agnes eventually assigns Sister Julia Wilkinson to escort the two around the convent. That night, after Julia discovers Abaddon dragging one of the other nuns away for soul removal, Agnes knocks her out and takes her to the basement with their other victims. The demons remove the souls of all the girls until only Julia is left. While Abaddon and Agnes remove the soul of one of their captives, Henry and Josie arrive and exorcise the other two demons involved in the plot. As Agnes is in the other room, she is not exorcised and watches as Abaddon confronts Josie and then possesses her. Agnes questions Abaddon about her plans to infiltrate the Men of Letters and study them. Abaddon tells Agnes she plans to study and then destroy the order and commands Agnes to play dead and continue their work without her. Agnes pretends Josie exorcised her so that Henry wouldn't be suspicious and Abaddon is able to successfully infiltrate the Men of Letters and destroy them.
Following Abaddon's departure, Agnes presumably kept up the work of stealing souls as Abaddon ordered.
In 2014, Agnes was continuing Abaddon's work in secret and was still using the now-closed convent as her base. While people, once, would stroll right in due to their religious beliefs, they no longer did that due to "perverts" in the church; Agnes, therefore, adapted by having another demon possess a local man named Mr. Richie; the demon would drive around within an old St. Bonaventure van, kidnap people, and steal their souls. After the return of Abaddon and the beginning of her crusade to take over Hell, Agnes' operation ended up being one of several that the Knight of Hell was using to build up her army of demons loyal to her.
As in 1958, the soul-collecting operation drew attention, this time from Sam Winchester, Henry's grandson who, like his grandfather, believed he was dealing with a case of demonic possession. While investigating, Sam realized that the people were acting more like he did when he was soulless than someone who was possessed. While Sam was investigating, he encountered Julia Wilkinson, who told him the story of what happened in 1958. Having seen a picture of the St. Bonaventure van next to the vehicle of one of the victim's before they started acting weird, Sam realized that the convent was Agnes' base and went there to stop the plot. In the basement of the convent, Mr. Richie attacked Sam who quickly killed him. After Sam found the five souls Agnes had stolen, Agnes herself confronted Sam and after throwing him into a pillar, explained Abaddon's plan. Having lost the demon-killing knife, Sam quickly starts an exorcism, but Agnes grabs him by the throat to stop him. Sam then activates a recorded exorcism on his phone and tosses the phone away so Agnes can't stop it. Affected by it, Agnes desperately crawls to the phone to stop it before she can be exorcised. Agnes manages to smash the phone in time, but while she's distracted, Sam retrieves the demon-killing knife and stabs her in the back, killing her. He then releases the souls she had stolen which return to their rightful owners and restore them to normal. While Agnes' operation is stopped, hunters later see signs of the other factories Agnes mentioned. The revelation of Abaddon's plan also gets Sam fully on board with Dean's obsession with killing Abaddon.
Powers and Abilities
She has standard demonic powers and abilities. But, as a soul collector and demon recruiter, she has some abilities which are unique to her.
- Demonic Possession - Like common demons, she required a human vessel or "meat suit" to travel on Earth.
- Super Strength - She was able to overpower and choke Sam and smashed his phone into pieces with one hit, despite her body being that of an old woman.
- Immunity - She possessed resiliency to holy ground, something which other lesser demons do not. Not only can she walk on holy ground, she turned a convent into her lair.
- Immortality - Like common demons, she has an indefinitely long lifespan and an arrested aging process.
- Soul Collecting (possibly) - She can collect her victim's soul and contain them in jars, although how and what method she used to do this is not known, therefore it is unknown if she relied on her own power to do this.
As a regular low-level demon, Agnes possessed all the weaknesses inherent to demons.
- Exorcism - As a regular demon, Agnes could be exorcised. She was clearly affected by an exorcism when one was used against her but prevented it from being finished.
- Demon-Killing Knife - Agnes was killed with the knife.
- High-Tier Demons - Agnes was subservient to Abaddon.