Gwen and Sierra

This article focuses on the interactions between Gwen and Sierra.

Overview
The conflict between Gwen and Sierra is mostly one-sided on Sierra's side, due to her intense jealousy of Cody's feelings for Gwen, as well as her disgust at Gwen for kissing Courtney's boyfriend Duncan during Total Drama World Tour. It reaches a high point after the events of Greece's Pieces, when Tyler reveals that Gwen and Duncan kissed in the lavatory confessional. When Sierra finds out about the incident, her hatred for Gwen intensifies, and ultimately ends in her helping Courtney vote Gwen off two episodes later. The conflict ended as not one-sided, as even Gwen started to dislike Sierra.

Super Happy Crazy Fun Time Japan
Gwen is grossed out after watching Sierra sniff Cody's shoe and seeing its lace come out of her mouth. After winning the challenge, Sierra calls for a group hug, but she tells Gwen, Courtney, and Heather to "back off" once they start coming closer to her and Cody.

The Am-AH-Zon Race
Gwen is disturbed when she finds out that Sierra is using a pizza box as a laptop and an actual mouse as a computer mouse. She quickly rejects Sierra's offer to use it after she finishes with it. When Chris asks for a team member to carry Cody's EpiPen, Cody begs Gwen to take it instead of Sierra, which she reluctantly agrees to do, much to Sierra's dismay. Sierra complained about this arrangement, claiming that she knew more about Cody's life threatening allergies than anyone. When they are caught by the Zing-Zings, Heather orders Gwen to reach into Cody's pockets for the lantern's batteries, Sierra then complains about not being the one reaching into Cody's pockets. Later, Sierra is annoyed by Gwen's snoring, claiming that she was driving her crazy. After their team lost the challenge, Sierra and Courtney glare at Gwen when she wakes up and asks if they had won. Like Heather, Sierra thinks Gwen is responsible for jinxing their team. She then agrees to vote Heather off for their loss, if Gwen promises to stop being nice to Cody.

Can't Help Falling in Louvre
After hearing Sierra cry throughout the first challenge, Gwen furiously yells that she can not take it anymore, and along with Courtney and Heather, leaves her behind with Cody, telling him that he needs to deal with her alone.

Greece's Pieces
After learning about Duncan and Gwen's kiss, Sierra sides with Courtney by ordering Cody to lose the challenge, so that the team can vote Gwen off.

The EX-Files
In this episode, Sierra is shown to have developed a strong hatred towards Gwen. She makes a paper cut-out of Gwen and then bites its head off, while singing an altered version of the nursery rhyme Rock-a-bye Baby. Later, in the confessionals, although she says that she saw Duncan and Gwen's attraction coming since season one, she still believes that stealing other girls' boyfriends is wrong. When a lizard climbs up Heather's leg and everyone ends up in the middle of the minefield, Sierra immediately blames Gwen for leading them to the trap, labeling her as the "New Heather." Though she doesn't sing in Boyfriend Kisser, she does make a line about how obvious Gwen and Duncan's attraction was. At the base, none of the teammates is able to find an artifact, until Gwen finds the alien cube. Sierra and Courtney are the only ones upset at her, seeing as how she won the challenge and made herself safe.

Picnic at Hanging Dork
In the first class section, Sierra and Courtney glare ominously at Gwen. Sierra even does not bother Cody for a while because she is too focused on hating Gwen. Sierra joins Courtney's alliance to vote Gwen off if they lose. Additionally, Gwen tried to be in an alliance with Cody, telling Cody she would help get Sierra voted off after Courtney if he joined forces with her.

Sweden Sour
Sierra is delighted that Gwen is gone and refers to Gwen, calling her an enemy in a confessional. She claims that Gwen's absence will lead Cody to realize who his true love is, while pointing at herself. Sierra is also mad when Cody constructs a huge wooden replica of Gwen's face.

Awwwwww, Drumheller
When Cody starts talking in his sleep and reveals that he is having a dream about him and Gwen, Sierra quickly wakes him up. When he asks what happened, she tells him that he was having a nightmare.

The Am-AH-Zon Race
Despite being jealous of Gwen's hold over Cody, as well as angry at her for cursing the team with her good luck prediction, Sierra agrees to vote Heather off instead of her, on the condition that Gwen wouldn't "be so nice to Cody."

Greece's Pieces
Prior to discovering the kiss, Sierra approves of the concept of a "Gwuncan" relationship. Later, when Courtney finds out about the kiss, Sierra physically restrains her from attacking Gwen with a worried look on her face.