The Morrígan appeared with two of her Dark Fae bodyguards, upon hearing of Bo, the unaligned succubus. She and her guards go to The Ash's Light Fae headquarters. Lauren attempts to stop her but to no avail as The Morrígan insisted on seeing Bo and pushed past the human.
She interrupted The Ash's interrogation of Bo, wanting Bo for the Dark Fae. When The Ash orders Lauren to take Bo for analysis, The Morrígan orders her guards to take Bo instead. Though some fighting between the Light and Dark occur, The Ash soon puts a stop to it, telling The Morrígan that Lauren needed to examine her, and that the two of them needed to talk.
While The Morrígan doesn't believe that Bo's as ignorant as she says, The Ash is unsure, and he wants the two of them to work together to solve the problem. The Morrígan doesn't really want to, and she thinks that if they'll be ridiculed by the other Fae counties for having Bo hidden from them, that it'd be best to kill Bo and get it over with. She views Bo as a threat as long as she is neutral, so the Ash decides that they force her to choose a side, the old fashioned way.
At the Glass Factory where Bo is to be tested, The Morrígan has a private meeting with Bo, where she attempts to get Bo to spill any information on herself that she may have. The Morrígan also explains that Bo will be tested to join a side, and that neutrality isn't an option. The Morrígan also shows sympathy for Bo, on her having to be alone for so long, and that she should really consider which side she wants (The Morrígan subtly hinting that she should join Dark) before The Morrígan makes her leave.
The Morrígan witnessed Bo killing a Troll and defeating a Pain Eater. The Morrígan is furious when Bo decides to remain neutral, and still wants to kill her as she's more of a threat than she thought. Trick though manages to convince her and The Ash to leave her alive for the time being, as a means to unravel her mystery. Mayer, a Dark Fae, reveals that all the money he collects by using the luck of certain humans to win betting scores, goes straight to The Morrígan.
When Dyson is accused of murdering a Dark Fae Redcap named Ba'al, he asks for sanctuary at the Dal. The Morrígan brings two bodyguards with her as she goes to the Dal and demands for Dyson to be handed over. Upon refusal she has her bodyguards attack Bo and Dyson. Trick brings out a shotgun and tells The Morrígan that she can leave, though she vows that sooner or later she will "have Dyson's head for her wall". Dyson eventually decides his friends are sacrificing enough for him, and he goes to Vex's night club, Carpe Noctem. There he is captured by Vex and The Morrígan. Dyson is chained up and Vex tortures him while Silas watches as The Morrígan tries to interrogate him, though to no avail. When she starts to get bored she orders Dyson's death, but Bo, Kenzi, and Portia interrupt. They expose Silas as being the murderer over his love for Portia and to prevent Ba'al from killing her and that he framed Dyson. The Morrígan releases Dyson and watches as Vex begins to torture Silas.
When Kenzi's childhood friend Nate attempted to apply for an audition with The Morrígan's agency, Kenzi made a deal with The Morrígan to spare Nate and she rejected the audition in exchange for a future favour from Kenzi.
In Season 4, Evony convinced Lauren to join the Dark Fae and granted her a personal liberty that was denied to Lauren under ownership by The Ash, in return for which Lauren would serve as the scientist and physician for the Dark and do the The Morrígan's bidding. Unbeknownst to Evony, Lauren joined the Dark deliberately to help Bo behind the scenes.
In Of All the Gin Joints, after Evony made a surprise visit to Lauren when she was getting ready to move out of the Light Fae apartment and into one provided by the Dark clan, they flirted and kissed before Evony departed. Lauren, however, did it to obtain a sample of Evony's DNA.
In Origin/It Begins, Lauren had created a biology-mutating serum with the DNA and taking advantage of Evony's narcissim offered herself to her. Evony ingested the serum during coition and was transformed into a human, with all her abilities gone.
Evony presents great talent for malice and cutting remarks. In addition to a clever and manipulative streak which she is able to use to exploit both Fae and humans alike; a character trait that shines through her abuse of human artists, stealing their royalties to service her own goals.
Marquise is quick to remind anyone she views as a threat or disrespectful of her ability and willingness to see them suffer when they step out of line making her a feared Fae leader.
As a Leanan sídhe, Evony has the supernatural skill of absorbing the talents from artists and musicians, which fits well for her profession as a talent agent, seeking underlying talent and acquiring them for her benefit.
In Into the Dark, it was revealed that she can also drain talents to the point where recipients are literally reduced to a puddle. (This ability does not seem to be a common trait of a Leanan sídhe, as even Trick did not seem to be aware of it.)
Massimo: Her human son. He addressed her as "Evony". She treated him with disdain and belittled everything he did.
- It is interesting to note that while she is the leader of the Dark Fae, she has been shown on occasion to be manipulated or deceived. In It's Better to Burn Out Than Fae Away, her assistant Bianca tried to undermined her plans by controlling her subjects. In Into the Dark, she is twice taken advantage of for another Fae's personal gain. In ConFaegion, she was shown willing to risk the Fae world to settle a petty vendetta by infecting Vex with a contagious parasite so that it could infect Bo (which it thereafter transferred into Dyson and Tamsin).
- In Into the Dark, Paulo mentions that he heard everyone calling her (The Morrígan) a "MILF". The acronym MILF stands for: "Mother I'd Like (to) F_ _ _". It's a vulgar slang for a sexually attractive older woman (usually one that is also a mother). In Origin/It Begins, it's revealed that she is Massimo's mother.
- As The Morrígan, she has yet to call in a favour (to be determined by her) that Kenzi owes her. (Kenzi promised to do whatever she wanted if she left her childhood friend, Nate, alone and not drain him of his talents.)
- Given the constant theme of BDSM surrounding her and Vex it's possible her last name is a reference to the seventeenth century french erotic author Marquise de Sade.  [Note: this is speculation by fan.]
- 1.01 It's a Fae, Fae, Fae, Fae World
- 1.11 Faetal Justice
- 2.06 It's Better to Burn Out Than Fae Away
- 2.15 Table for Fae
- 2.21 Into the Dark
- 3.03 ConFaegion
- 3.06 The Kenzi Scale
- 3.12 Hail, Hale
- 3.13 Those Who Wander
- 4.03 Lovers. Apart.
- 4.05 Let the Dark Times Roll
- 4.06 Of All the Gin Joints
- 4.12 Origin/It Begins
- 4.13 Dark Horse
- 5.04 When God Opens a Window
- 5.07 Here Comes the Night