When the Charmed Ones were constituted, Parker and his half-brother were assigned various roles to help in their father's mission to raise The Source of All Evil. Part of Parker's role was to infiltrate the Charmed Ones through Maggie.
Parker always knew she was a witch (and a Charmed One), but he pretended to be mortal until the events of Christmas 2018.
Throughout the Series
Parker defends Maggie from her rude customer, and she is immediately attracted to him. Though, later on during the Halloween party, Lucy introduces Parker as her boyfriend.
Maggie has a conversation with Lucy about being on the verge of failing World Literature. Not wanting to "bring down Kappa's GPA", Lucy asks Parker to tutor Maggie, and he agrees. Later, Parker shows up to the same place where Maggie and her sisters are exorcising a demon from Angela Wu, claiming to "look for a place to hide fireworks". During this conversation Parker almost sees a possessed Angela, and to distract him Maggie quickly pulls him in and kisses him.
Lucy starts to suspect that Parker is cheating on her, so she asks Maggie to figure it out. Parker states that he wants her, not Lucy. So, Parker and Lucy ultimately break up.
Maggie starts having romantic dreams with Parker. When she meets up with him, he notes that she has been avoiding him, Parker tells her that Lucy gave them an okay to date because she has already moved on. During this date, they have a deep conversation about "feeling like they aren't enough", especially compared to their family. They then start to kiss, when Maggie overhears Parker thinking that he does not want Maggie to find out the truth about him. This gets Maggie concerned. She starts investigating to figure out what Parker is hiding. She goes to the fraternity house and finds Parker injecting himself with a needle. She assumes that he is doing drugs and runs away. Later on, Parker comes to explain himself to Maggie. He says that he was taking medicine because of a rare autoimmune disease that he does not want people to find out about. Maggie concludes that is the secret Parker was keeping from her. They both share a passionate kiss.
In reality, Parker does not have an autoimmune disease. It is revealed that he is the shadow demon that the Charmed Ones had been trying to stop from stealing the Scythe of Tartarus.
Parker tries to convince Maggie to take an internship at his father's company since all interns must submit a blood sample for testing. He tells Maggie that he needs a plasma transplant for his condition but he doesn't have many potential blood donors since he's keeping the condition a secret. So, he asks Maggie if she could get tested to see if she could donate blood to him. Maggie agrees to get tested and give her blood to Parker.
He gives the amulet to Maggie as a Christmas present in his ploy to steal the Charmed Ones' powers, but upon realizing his own feelings for Maggie, he removes the amulet, thus restoring their powers. When Hunter breaks out a fight in the manor's backyard, Parker exposes his powers and identity in front of the sisters in an attempt to protect them. He then tries to explain to Maggie, but she refuses to listen. Hunter later returns to settle the score, but Parker comes to their rescue and tries to banish Hunter to hell. However, he grows weaker with each attempt and the sisters help out. Though they succeed in banishing Hunter, Harry is pulled in as well.
Maggie is still dealing with the fallout from the revelation that Parker is a demon or at least half-demon. She feels very betrayed by Parker, and also feels like her powers betrayed her by not revealing Parker’s secret to her. Tired of all the pain she feels, Maggie decides to use the Book of Shadows for a spell that’ll take her pain away.
She finds it in the anti-heartbreak spell however due to it her powers don't work. Dante is able to break free and now Maggie is sent to Tartarus.
Mel and Macy rush to Charity for help, they argue, and then learn that Alistair took it. Mel and Maggie have no choice but to ask Parker for help.
When they visit Parker in his dorm, he feels very guilty about the events last year at Christmas and is looking for a way to help Maggie. He offers to assist Mel and Macy in their efforts to steal the Harbinger of hell from Alistair’s office.
Back in Tartarus, Maggie is being tortured with her own memories of Parker and her mother's death.
She later is set freed with Harry, but they encounter Alastor as they reunited with Macy and Mel. Back at the Vera manor after that encounter, Maggie tells her sisters she can’t believe she tried to take away her feelings with a spell and needs to deal with it. But sadly, now she can’t stop thinking about Parker. Parker soon arrives at the manor to check in on Maggie, who is under the impression he double-crossed her sisters and is still very betrayed. Before Parker leaves, he tells her that whatever happened between the sisters and Alastor spooked him so much it caused him to leave town, so he will not be a problem for them for a while.
Parker doesn't show up, but Maggie says Lucy that he's a monster and she wants nothing to do with him.
Maggie runs into Lucy who tells her about the stoplight party at Phi Delt. At the party Maggie and Lucy talking about Parker when he and Maggie look at each other for a brief second. As hard as Maggie tries to find another guy, she can't.
When Maggie gets two skinny margs for her and Lucy, she is forced to talk to Parker as he is the one serving the drinks. Maggie mentions how Parker has ruined dating for her as he is the only one she can be completely honest with, know who she really is, and why he is a terrible person for lying to her.
Later, Maggie is held hostage by another witch, Cyd in the bathroom to lure Macy there in order to kill Knansie. As Macy arrives at the party, she spots Parker and asks where the bathroom is, so she can save her sister. Parker and Macy look in each stall and shower hoping to find Maggie who is trapped. They shared two hugs after she was saved.
The next day, Maggie tells Parker she doesn’t hate him making Parker wonder what it meant about where they stood. Maggie then replies "It means I don’t hate you and that has to be enough. For Now." She walks away and Parker smiles.
Parker informs Maggie of a death that could be of something supernatural. He invites her to the memorial for the guy in his film studies class who died. At the memorial, Macy mentions how she doesn’t need Maggie’s boundary violating powers to tell Maggie is still into Parker. She responds to Macy by telling her that she can’t get over the way Parker and her met as well as the way he made her feel stupid when he manipulated her.
The supernatural being behind the death was a pixie named Chloe. She was targeting white guys specifically in the film department, so Maggie texted Parker to watch out. Before he read the entire message, Chloe approaches Parker with a golden retreiver puppy and her pixie dust makes him whimsiful. Harry told Maggie that demons would be immune but because Parker’s mom and Macy were working on a serum to depress his demon powers, he was affected. Maggie notices Parker skipping realizing he was affected and she was able to sober him up from the pixie dust using her powers.
As Maggie and her sisters were on their way to the film studies building on the campus, Parker was waiting by the doors to assist. Maggie and Parker argue about him always swooping in to save her. She said he could help as they were down a Whitelighter.
As they were trying to catch Harry, Parker asks Maggie if he was this annoying when he was on pixie dust. Maggie tell his he was worse and they smiled at each other.
The next day, Maggie wonders where Parker went off to the night before and when she finds him she notices he found the puppy Chloe gave him. Parker decides to keep the dog as he always wanted a dog but never did because of his father. Maggie then says, ”That’s so sweet. And human. I hope I don’t regret this.” Parker replies by saying, “Regret what?”
Finally the two share a kiss and get interrupted by the puppy.
They attempt to get their relationship to the next level however that's not because Maggie’s private area shoots out a beam of light that throws Parker across the room. At the Manor, Maggie brings up the sex issue to Macy. Macy suggests it might be a force field she manifests out of emotion because she’s still worried about being hurt by Parker deep down in her mind. Back at Parker’s place, Maggie and Parker talk about what happened earlier. She explains that she manifests energy out of raw emotion, and she had manifested her own fear of Parker hurting her. They try to hook up again, but Parker has too much on his mind and storms out. Back at the Vera mansion Maggie vents about her frustration with sex lately and gets unexpecting but well received advice from Heaven Vice's Gideon. After rectifying the Heaven Vice situation. Maggie and Parker finally get a chance, to be honest with one another about sleeping together, and Parker admits that his biggest fear is hurting her. They end up sleeping together—no shooting light out of any private areas this time.
Right in the middle of sex, Parker’s powers go haywire and they end up dropping into a dark abyss located below the Vera Manor.
Maggie switches bodies with Mel. Leading Parker to mistake Mel as Maggie before being filled in on the switch. After Parker kicks the offending brothers out of the fraternity for slut shaming. Maggie as Mel kisses Parker forgetting that's in her sister body leaving it little bit awkward for everyone watching.
. He and Maggie celebrate the good news of his demon cells are being being combated by his mother's serum prototype ,but are quickly interrupted by Lucy. Maggie, wanting to stay on Lucy’s good side now that she’s rushing Kappa again, invites her to join them. Lucy rushes off to pick up a round of bellinis but as she’s mesmerized by Alastair, she empties a vial of a mysterious liquid into Parker’s drink. Maggie is concerned for Parker after she's alerted he fainted in the Phi Delta bathroom. Maggie visits him. Whom thanks to Alastair and Lucy has been infected with a demonic virus. According to Parker, only his father will be able to cure him and it’s his sick way of trying to force his estranged son to reach out to him which he has no plans to do. Maggie vows to find an alternative solution for Parker before it’s too late.
Maggie is prevented from seeing Parker by his mother who claims his condition has worsen leading Maggie to get demon blood for him.
Hunter manipulates Parker by shapeshifting into Maggie and breaking up with him in order to push him over to the dark side.
Maggie kills Hunter partly as revenge for manipulating his brother and ending their relationship.
Maggie is kidnapped by Alastor to blackmail Parker into becoming the Source. However, Macy thwarted his plan by taking Parker's place and becoming the host for the Source instead. Alastor was at first estatic to be in the presence of the Source, but Macy, with the Source's enhanced power, vanquished him on the spot. They're relived to both be safe and finally free of Alastor's manipulation.
After the death of his father Parker leaves Hilltowne and Maggie in order to control his inner demons which leaves Maggie heartbroken as he declines her help.
Maggie stills wonders about Parker from time to time, even briefly considering asking his half-sister if she knew where he was.
Parker returns, and asks Maggie to marry him.
Parker learns from Macy Vaughn that Maggie has accepted his "death" and she is now happy. He selfishly stated that he didn't want her to move on, and refused to help Macy until she agreed to take his letter for Maggie and give it to her.
Maggie finds out that Parker is alive in this episode. Indignantly, she confessed to her sisters that she felt relief when Parker died, because of the person he became and the things he did, it was just too hard to reconcile with what they used to have and who he used to be. Maggie said it was almost easier when he just all went away.
Parker makes another mistake, succumbing to the persuasions of Godric to return to the demonic life. He is released from prison and helps Godric overthrow Abigael. Parker was ready to kill his half-sister for that, but when Godric begins to threaten the life of Maggie, he abandons the plan and moves with Maggie and Macy to a safe place.
Later, in the Command Center, Parker tries to apologize, but Maggie only feels angry and annoyed with him. However, when Macy said her that he is their only chance to save Mel Vera, Maggie to let Parker help them. After being rescued from Godric, Parker asks Abigael to take his powers and make him completely mortal.
In SafeSpace, Seattle, Parker calls Maggie out for a tete-a-tete and tells her that there is nothing demonic about him anymore and tries to get their relationship back for the last time. Despite the fact that Maggie forgives him and supports his attempt to become better, she calmly says that this does not change anything between them, she does not want to go back to Parker and now their paths must separate. Parker agrees to this, and when he leaves, Maggie finally breathes a sigh of relief and begins a new chapter in her life.
- Maggie and Parker's relationship is a mirror reference to the original series' couple, Phoebe and Cole. Their relationship lasted two years before it ended.
- Both Maggie and Parker have older half-siblings: Mel Vera and Hunter Caine.
- In "Jingle Hell", Maggie learned of Parker's half-demon status and ended their relationship.
- They officially got back together in '"'Manic Pixie Nightmare".
- As of "The Rules of Engagement", Maggie thinks Parker is dead, but she's already mentally coping with this loss, because she believes that if they continued to be together, his demonic side would still always stand between them.
- In "Sudden Death", Maggie meets Parker alive, and she refuses to forgive him for what he did to her.
- In "The Enemy of My Frenemy", Parker becomes fully mortal and apologizes to Maggie for everything. Maggie forgives him, but nevertheless finally breaks off their relationship, wanting to move on without Parker.