Heather and Sierra

This article focuses on the interactions between Heather and Sierra.

Overview
With Sierra being one of Heather's new potential targets for an alliance at the start of Total Drama World Tour, Heather decides to go after her from the start. However, having seen the first two seasons multiple times and knowing of Heather's reputation on the show, Sierra is fully aware of what Heather has in mind and decides to use Heather's manipulations for her own advantage. Ultimately, they end up together on Team Amazon.

Both attempt to manipulate the other for their own motives, going from complete friendship to utter disrespect for one another. Heather admires Sierra's knowledge of the show, but sees her as utterly insane, while Sierra sees Heather as a fellow female friend, but knows of her evil and manipulative manner. Ultimately, by the end of the season, the two put their differences aside in order to get rid of Alejandro.

Celebrity Manhunt's Total Drama Action Reunion Special
When Sierra says that she knows everything about everyone, including their dental records, Heather scoffs at her and calls her a stalker.

Walk Like An Egyptian - Part 1
Heather tries to form an alliance with Sierra to counter Alejandro's possible alliance with Lindsay. Heather pretends to like Sierra, but is actually very annoyed by her. In the confessional, Heather says "I do not heart the new girl." Heather chooses to ally with Sierra and Cody during their journey under the pyramid, working together to escape from the "mummy" chasing after them. While the two go through the pyramid, Sierra sets off a trap that sends a row of arrows toward Heather's head, Heather is visibly angry, but she is able to control herself and pretends to forgive Sierra. Heather joins Sierra in a group hug with Cody, although she was very reluctant to do it. Sierra seems to be unaware that Heather dislikes her, which appears to be quite odd, since Sierra supposedly knows everything about the contestants and should know of Heather's manipulative nature. Heather slowly and awkwardly joins in a group hug with her and Cody once they cross the finish line.

Walk Like An Egyptian - Part 2
Heather quickly agrees to switch Izzy for Sierra, as she believed Sierra's weaving skills would be vital for the challenge. She starts to regret this after she realizes that only Izzy was able to control their camel.

Super Happy Crazy Fun Time Japan
Heather stood up for Sierra, saying that the team should consider Sierra's opinion when Courtney was saying she should be team leader.

Broadway, Baby!
Heather reaffirms her need to manipulate Sierra (and Cody by consequence) in order to survive on a team with Gwen and Courtney when they publicly acknowledge that they want to eliminate her next. When Sierra wanted to hug Heather, she (albeit purposely) rejected. However, Sierra states that she knows that Heather is playing her, so she's playing Heather back by pretending to be played. Later, when Team Amazon is receiving their rewards, Heather tells Sierra to not talk to Chris so that he'll forget how creepy she is, however, Heather quickly corrects herself by calling her "special" instead.

Slap Slap Revolution
Heather is seen sitting with Sierra in the winner's class cabin. Sierra is telling Heather about how she became the president of her fifteenth Total Drama fan club. Heather isn't very interested by this and changes subjects, asking if Sierra has any idea of who will be eliminated next. Sierra confirms and states that Team Chris Is Really Really Really Really Hot is the next to lose, due to overconfidence. Right after this, Sierra appears in the confessional and says that every time she thinks Heather is using her, she makes a little notch on her belt. She tales it off from her pants, showing her underwear and seven notches in her belt. This may confirm that in previous episodes, Sierra was truly aware of Heather's tactics, but didn't show it. During the sausage stuffing challenge, Heather points out that it is Sierra who is making them lose due to making a statue of Cody out of their meat instead of her when accused by Courtney of not helping out.

The Am-AH-Zon Race
When Heather found out that the Zing-Zings were just teenage Peruvian actors, Sierra comments that Heather isn't the goddess she thinks she is. Sierra decides to join Gwen and Courtney in voting Heather out, but in return, made Gwen promise that she wouldn't be as nice to Cody. She, along with her other teammates, was shocked when Chris revealed it was a fake elimination ceremony.

Can't Help Falling in Louvre
Heather shows consideration for Sierra during her singing of Paris in the Springtime, yelling at Cody to take care of her and make sure she gets what she needs to get over her sorrow. However, this may have only been because Sierra's crying was annoying and ultimately bringing the team down.

Jamaica Me Sweat
Heather calls Sierra "fanzilla" when she ends up splashing her, Courtney and Gwen with her dive.

Sweden Sour
While trying to get Alejandro's attention away from Courtney, Heather claimed that she got some gum on her butt. However, Sierra ruins it as she points out to Heather that she doesn't have any gum on her. Later, when Heather was trying to hit Cody with a metal hammer for building a wooden replica of Gwen's head, Sierra started chasing her with a metal rod, and they briefly engaged in a fight that knocked out Courtney.

Rapa Phooey!
After Alejandro chooses Cody for his flight partner in the previous episode, Sierra uses Heather as a psychiatric adviser to help try and figure out what is wrong with the two of them. As Sierra vents about how she misses Cody due to Alejandro choosing him for his partner in first-class, Heather rants in the confessional about how Sierra's insane obsession with him is not helping anything. She does not say this to her face though, because she wants Sierra to remain her ally. Sierra was making fun of Heather and Alejandro and how they are obsessed with each other. Even though paired with her for most of the challenge, Sierra admits that alliances don't work and that she refuses to ally with anyone that isn't Cody. After "giving birth" to a second Cody in the form of a condor chick, Sierra becomes frustrated when it chooses Heather as his mother over her, even ruining her performance in the second part of the challenge due to losing frustration at Cody, Jr. going after Heather mid-way up to the nest. By the end of the episode, Heather admits finally that Sierra is insane and can't be trusted in any true alliance.

Awwwwww, Drumheller
While talking with Alejandro about the reason for  her inviting him to first class with her she says that if she separated Sierra and Cody that Sierra would try to get her eliminated. After Alejandro makes a fake digital photo of Cody and Heather sleeping together in the loser cabin, Sierra becomes angry at her throughout the challenge. While the contestants were searching for stuff to use in the design-o-saur challenge, Sierra squirts glitter glue in Heather's face out of her fury, to which Heather responds, "Real Mature!". Later, Heather voted for Sierra's dinosaur as the best one created. Sierra also voted for Heather's dinosaur because she loved the idea that it was a Chris dinosaur and said she'll have to remember that idea. After Sierra won the first part of the challenge, she attempts to use her newly received post digger to attack Heather. Eventually, Sierra found out about the truth between Cody and Heather, and the photo was a fake. When Heather was in the confessional, Sierra popped in and Heather jumped away and begged her not to murder her. Later, when Sierra accidentally blows up the plane, Heather appears to be concerned.

Planes, Trains, and Hot Air Mobiles
When Cody dug up Sierra from the rubble, Heather went and got her a wheelchair and a green feathered hat from Rapa Phooey!. In the confessional, Heather says that she knows what it's like to be bald and that no girl, crazy or not, should have to be bald on television. Later, Sierra states to the fireworks salesman that she can't let Heather win.

Hawaiian Punch
In Heather's ending, Sierra cheered for Heather when she kicked Alejandro in the groin and won the season, along with the one million dollars prize. She also looked concerned when Heather and Ezekiel fought over the million dollars.

Opening sequence
Heather and Sierra are seen fighting over a treasure chest underwater.

Trivia

 * Both have lost their hair in the first season they participate in and two seasons later, their hair grew back and is tied into a ponytail.
 * Both of them appeared in every episode of a season despite not being a finalist.
 * Coincidentally it was the season in which they lost their hair.