SPOILER WARNING: Plot details follow. Caution is advised!
We have eternity, so you'll grow to love me the way that I love you.

–Heidi to Simon Lewis, Familia Ante Omnia

Heidi McKenzie is a vampire who was once a mundane girl who frequented bleeder dens.


Early life

Heidi did not have a particularly good relationship with her family.[1] When she was 16, she went to a bleeder den for the first time,[2] looking for an escape. She was immediately addicted and became obsessed with the idea of becoming a vampire herself.[1]

TMI215 Heidimon06

Late in 2016, Heidi went to one where she was a frequent customer. She spotted the vampire Quinn entering with a first-timer Simon Lewis and approached them. Quinn introduced them, and Heidi bit her lip, making it bleed to entice Simon. Though initially hesitant, Simon gave in, and the intoxicated pair stayed together and went outside, where she continued to let Simon feed on her.

After her time with Simon, Heidi crossed paths with Quinn. He fed on her, through her ankle, and was unable to control his hunger until he, apparently accidentally, drained her of blood and killed her. Simon's fingerprints were taken from her bracelet and he became the primary suspect for the mundane police investigation into her murder. Simon returned to the bleeder den in hopes of remembering if he did kill Heidi and turned himself in to Detective Ollie who'd arrived at the scene, but Simon realized that she was killed by Daniel and killed him when he refused to take responsibility. Brooklyn vampire clan leader Raphael Santiago then encanto'd Ollie so she would close the case, telling her that her real murderer had disappeared and making her forget Simon.[3]

Turned for testing

Raphael, however, did not leave Heidi to simply die. Heidi ended up with vampire blood in her system, so when she died, she became a fledgling. Raphael rescued her from the morgue and helped her through her transition and had since kept her in the basement of the Hotel Dumort. Heidi took her Turning well, excited about the prospect of being a vampire, and often pestered Raphael about wanting to see her sire, Simon, while Raphael continued to insist that she still had some adjusting to do.[2] Heidi clung to her first impression of Simon when they met at the bleeder den, hopeful that he cared about her.[4]

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Raphael burning Heidi.

Meanwhile, she was also subjected to Raphael's experiments, in hopes of figuring out how to be a Daylighter like Simon.[1][4] He burned her with UV light, keeping her sedated with dagget root—a vampire tranquilizer.[5] Heidi grew more restless over time, desperate to see her sire again. Once, she threatened Raphael; Raphael made her believe that he was letting her go before drugging her again. When Raphael stepped out of the hotel, Heidi took the opportunity and escaped.[2]

After getting out, Heidi felt her thirst for blood and went to a blood donation unit truck to get some. She first stole bags of blood but decided to feed on the mundane worker onboard the truck instead. She'd drained him of his blood and killed him but, apparently upon remembering Raphael, she decided to Turn him.

Obsession with Simon

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Heidi in Simon's bed.

She then headed to Simon's boathouse, hoping to see Simon, but was met by Raphael instead. Heidie was able to fight him off and knocked him out with dagget root. As revenge for her suffering from his experiments, she chained Raphael down on a rooftop to be burned by the sun as soon as it rose. Meanwhile, the man she'd Turned and buried in the building's basement was killed by the Shadowhunters who also later released Raphael.[1]

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"You don't deserve him."

Heidi did not stop trying to pursue Simon. Using Raphael's phone, she led him to her new hiding place. Though Simon became sympathetic to her and offered to be there for her when she needed him, he pulled away when Heidi tried to kiss him and explained that he had a girlfriend. Heidi pretended to understand but followed him to find out who the girl was. She found him at the Hunter's Moon and saw Isabelle Lightwood giving him a kiss and mistook her for his girlfriend. She confronted Isabelle outside the bathroom but stood no match against the Shadowhunter, though Simon came in time to stop Isabelle from killing her or taking her in for attacking her.

Simon accompanied her back to her hiding place, and she was under the impression that he was on her side, only to be ambushed by members of the Praetor Lupus who sedated and cuffed her to keep her under control. The Praetor was meant to help her,[4] but her Praetors were killed by Jace a couple of days after. Jace stuffed her into a duffel bag and took her to Lilith.

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"Time for a good old family dinner."

Simon: "So what's your game plan? You're gonna make me feed on my family, and then what?"
Heidi: "And then we'll be free to start a new life together."
―Heidi and Simon, Familia Ante Omnia

Lilith manipulated Heidi into going after Simon's family, convincing her that letting his family know that he was a vampire, and them rejecting him, would force them together. Lilith also warned Heidi not to attack Simon as it would trigger his Mark. Heidi tied up his family and cut into Rebecca's skin to make her bleed. Simon provoked her by bringing up her past, but Heidi remembered Lilith's warning and laughed it off. To finally get what she hoped to accomplish, she released Rebecca and let her go to Simon, and when the hungry Simon finally fed on his sister, Heidi left.[6]


Season Two (2B) appearances: 1/20
Mea Maxima Culpa:
You Are Not Your Own:
Those of Demon Blood:
The Fair Folk:
A Problem of Memory:
Day of Atonement:
Alluded to only
A Dark Reflection:
Awake, Arise, or...:
Hail and Farewell:
Beside Still Water:
Season Three appearances: 5/22
On Infernal Ground:
Appears; eclipsed
The Powers That Be:
What Lies Beneath:
Thy Soul Instructed:
Stronger Than Heaven:
A Window Into an...:
Salt in the Wound:
Mentioned only
A Heart of Darkness:
Familia Ante Omnia:
Mentioned only
Lost Souls:
Original Sin:
Beati Bellicosi:
May be featured
A Kiss From a Rose:
To the Night Children:
May be featured
Stay With Me:
Heavenly Fire:
The Beast Within:
Aku Cinta Kamu:
City of Glass:
All Good Things...:


  • Heidi is an original character created for the show, but her role is slightly similar to one that Maureen Brown had in the books.[7][8]