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. Gwen, on the other hand, doesn't care too much about Sierra because of her stalker-like tendencies as well as her disgusting habits, but they usually seem to get along. When Sierra and the rest of Team Amazon find out that Gwen kissed Duncan, Sierra's hatred for Gwen escalates and she allies with Courtney to get rid of Gwen once and for all in an effort to make Cody start paying attention to her, and also because she believes boyfriend stealing is wrong. After Gwen's elimination in Picnic at Hanging Dork, Sierra becomes delighted, but then realizes that Cody misses Gwen, much to her own dismay.

Their conflict has subsided by Total Drama All-Stars, partially due to Cody not qualifying for the season. While Gwen remains disturbed by Sierra's habits, especially her attraction towards Cameron, the latter actually seems to have warmed up to her. Sierra is an avid supporter of Gwen's relationship with Duncan, having made several "Gwuncan" videos. Gwen also shows sympathy for Sierra when she is eliminated in Suckers Punched.

Celebrity Manhunt's Total Drama Action Reunion Special
Gwen is disturbed when Sierra reveals that she knows personal information about the cast.

Super Happy Crazy Fun Time Japan
Gwen is grossed out after watching Sierra sniff Cody's shoe and seeing its lace go up her nose and out through her mouth. After winning the challenge, Gwen calls Cody's helpfulness amazing, to which Sierra agrees, before calling for a group hug. But while hugging Cody tightly, she angrily tells Courtney, Gwen, and Heather to "back off" as soon as they reach closer for the group hug.

Anything Yukon Do, I Can Do Better
When Cody attempts to cuddle Gwen for warmth (much to her displeasure), Gwen simply pushes him to Sierra, whom happily hugs 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 is finished with it. When Chris asks one of the members on Team Amazon to carry Cody's EpiPen, Cody begs Gwen to take it instead of Sierra, who reluctantly agrees to do so, much to Sierra's dismay. Sierra complains about this arrangement, claiming that she knows more about Cody's life threatening allergies than anyone else on the team. 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 is driving her crazy. After their team lose the challenge, Sierra and Courtney glare at Gwen when she wakes up and asks if they had won the challenge. 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 with Courtney and Gwen.

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

Greece's Pieces
Prior to discovering the kiss, Sierra approves of the concept of a "Gwuncan" relationship. Later, when Courtney finds out about Duncan's betrayal, Sierra restrains her from attacking Gwen, expressing a worried look on her face, despite siding with Courtney by ordering Cody to lose the challenge, so that the team can eliminate Gwen from the competition.

The EX-Files
In this episode, Sierra is shown to have developed a strong hatred towards Gwen. She angrily 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 forces everyone to run into 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 comment about how obvious Gwen and Duncan's attraction was. At the base, none of the teammates are 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 does not interact with Cody for a while because she is too focused on her hatred for Gwen. Sierra joins Courtney's alliance to vote Gwen off if they lose. Additionally, Gwen tries to be in an alliance with Cody, telling Cody she would help him get Sierra voted off after Courtney if he joined forces with her, strengthening their dislike for each other.

Sweden Sour
Sierra is delighted that Gwen is gone and refers to Gwen as her 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. She says Gwen's head is empty and thought of the idea of cutting the replica of Gwen's face and used it as a boat, in which both Heather and Courtney agree.

Niagara Brawls
When it is first thought that Gwen will be returning, Sierra, along with Courtney and Heather, looks disappointed.

Awwwwww, Drumheller
When Cody's sleep-talking indicated that he was 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.

Heroes vs. Villains
Sierra tells Gwen that while many fans seem to be upset about her being in a relationship with Duncan, she understands and also states that their relationship is similar to her and Cody's. Gwen then sarcastically says their relationship is just like Sierra's. When Duncan asks Gwen for a kiss before jumping off the cliff, Sierra's enthusiastic stare at them makes Gwen push him off instead.

Saving Private Leechball
Sierra sneaks up on Duncan and Gwen whilst the couple are talking about Courtney, and tries to ambush them but accidentally flings her leech at herself. As it latches into her face, she comments dreamily that it feels just Cody's kiss, making Gwen wretch in the confessional.

No One Eggspects The Spanish Opposition
Sierra attempts to team up with Cameron despite them being on opposing teams now, and crazily pants like a dog. Gwen (who has now become friends with the latter) drags him away from the crazy girl. This causes Sierra to fall to her knees screaming, "Cam-ody!."

Suckers Punched
Sierra sighs in happiness when Courtney and Gwen rekindle their friendship. When the Villainous Vultures are given the chance to vote off one of the Heroic Hamsters, Gwen speaks for her team that they've elected to eliminate Sierra. She also seems to feel sorry for her. Before Sierra takes the Flush of Shame, Gwen also asks Sierra to say "hi" to Cody for her.

Trivia

 * In both seasons that they compete in together, one of them places fourth while the other places ninth.
 * They both appear in every episode of the season in which they place fourth, despite not being a finalist.
 * Both have been eliminated in the seventh episode of a season.
 * Coincidentally, in the season where they place fourth, both are eliminated on the spot by Chris due to angering him by destroying something belonging to him.
 * In Awwwwww, Drumheller, Sierra accidentally blows up the Total Drama Jumbo Jet.
 * In The Bold and the Booty-ful, Gwen uses bear feces as paint in an attempt to restore a painting of Chris that she accidentally smudged.
 * This conflict is directly connected with Cody's attraction to Gwen.