She first appears in "Wizards vs. Vampires On Waverly Place" and falls in love with Justin when she catches him spying on her family restaurant for his parents' restaurant. The two fight their parents for their love (similar to Romeo and Juliet) and, soon, are allowed to date and have a relationship despite the feud between their different families.
When she was born, her parents let her have a soul so that she could socialize in the mortal world, which makes her nice and down-to-earth, as opposed to most vampires, who are usually heartless and cunning. Being a young vampire, Juliet is also very slow in her development as a vampire, as her fangs have just started to come in (Wizards vs. Vampires: Tasty Bites), and she is only able to turn into a full bat as of "Three Monsters". Without blood, Juliet seems to age more and more. After drinking blood, her body returns to her teenage looks.
She mentions having relationships with Caesar and Galileo in the past. She worked at her parents' restaurant, The Late Nite Bite. In her bedroom, the basement, she has a chalk drawing of a sunny view.
In Wizards vs. Vampires: Tasty Bites, Justin tells Juliet he loves her (thinking that's what she was about to say). He was extremely pleased that she didn't freak out. In the next episode, Wizards vs. Vampires: Dream Date, Justin got frightened that their relationship was going too fast and chickened out of her invitation to a lake. However, he got to her half-way to the lake on the carpet. In the sky, she told him that she loved him too.
In the final part of the Wizards vs Vampires saga, Wizards & Vampires vs. Zombies, Justin asked Juliet (at the Best Night Ever Prom in front of everybody) to go steady with him. Her answer was cut short by Zombies crashing Alex's Zombie Prom. After the dance-off, Juliet agreed to go steady with Justin and the two shared a kiss.
Juliet returned in the episode Three Monsters. Juliet and her family were put in danger when Justin accidentally turned in her family to the monster hunter council. She was temporarily saved when Alex switched her scent with Harper's to confuse the monster hunters. Juliet was then finally saved by Justin who showed two other monsters to the monster hunter council so Juliet would be saved.
In Night at the Lazerama, Juliet goes with Justin on his monster hunt for a mummy. They go to a museum, where they become trapped in the mummy exhibit with a glass roof in which Juliet couldn't stay under because of the sunlight, which can kill a vampire. Justin then made a selfless decision when he decided that Juliet needed to become the mummy's slave in order to save her life. Justin promised to find and destroy the mummy one day to get her back. She was last seen walking away fanning the mummy with her bat wings.
In Wizards vs. Werewolves, she is found and saved by Justin. In the episode, it is revealed that she used to date Mason Greybeck, but she says that her soulmate is Justin. When Mason attacks Justin, she uses her vampire powers to fight him and ends up losing her vampire powers due to Mason scratching her. After that, she becomes her true age (though this doesn't make much sense, as if she lost her powers of immortality, she would have likely perished) and is forced to leave Justin, making him heartbroken, but since she did not die it is possible she might still have some supernatural power left.
In Moving On, Alex and Harper want to help Justin move on over Juliet. So, Alex turns Harper into Juliet so they go on a date and "Juliet" (really Harper) tells him that she loves Zeke and she is Harper. At the end of the episode Justin goes on a date with Sarah, a girl Justin had met at the sub shop a few days ago, an elderly Juliet is seen smiling at Justin while he's on his date. Moving On marks the last appearance of Juliet Van Heusen in the third season. She returns in the final part of the Special Wizards in Arpt. 13B, named Wizards vs. Everything. Gorog captures Juliet's mind in the forest after she and Justin broke up. In the end, Gorog is defeated, and Juliet is released and given back a youthful appearance along with her vampire powers.
In "Who Will Be The Family Wizard", she arrives at the Wizard Competition late but cheers for Justin right away. She then sits next to Mason and they discuss their past, and how they have no hard feelings and they start to get along. She returns for the second part of the competition and cheers for Justin. She was then glad when Justin became Professor at Wiz Tech.
- Juliet and her parents are level 6 monsters
- Juliet was given a soul at birth so she is nicer than most vampires.
- Her parents have not appeared since the Wizards vs Vampires saga.
- When Juliet goes without drinking blood, she gets older in appearance. However, she returns to her younger state when she drinks it.
- She may like AB positive as a flavor of blood.
- While Juliet states that exposure to sunlight will kill her in Night at the Lazerama, she has been shown walking around unprotected in broad daylight to no ill effect in several episodes beforehand, although this may be due to her recent status of gaining her fangs.
- She works at Late Nite Bite, which is owned by her parents.
- She only eats healthy foods.
- She believes that Justin is her soul-mate.
- Juliet has been to 20 proms, counting Justin's and presumably, Mason's.
- Vampires cannot stand the smell of pumpkins. The Van Huesens explain that people began putting pumpkins on their doorsteps at Halloween in order to ward off vampires.
- She wears vanilla-scented perfume in order to hide her true vampire scent of death and decay.
- Her father's (Alucard) name is Dracula spelled backwards.
- There was no notice about Juliet's parents after she disappeared.
- Even though Juliet's parents don't appear the Late Nite Bite is still always seen in the background.
- Juliet and Mason both lost their abilities at the end of "Wizards vs Werewolves". However, in Wizards Unleashed", Mason gets his abilities back because of some magical musical instruments the Russo kids played. If Juliet were to return, they could do the same thing to her like when Gorog made Juliet look younger and gave her vampire powers back.
- Juliet returns in Wizards vs. Everything.This marks her reappearance since Wizards vs. Werewolves and her first appearance in season 4. She also appears in the series finale Who Will Be The Family Wizard.
- She is currently dating Justin Russo.
- She and Rosie are the only girlfriends that Justin has had for more than 2 episodes.
- Her parents sleep in coffins in the wall.