Chris McLean: Does he put the contestants in danger merely as an act because mortal danger equals high ratings? Or is he really that sadistic from day one? Or did it start as an act, then he became more sadistic the longer he hosted the show?
Chef Hatchet: A guy that's just going along with whatever the hell Chris is up to and is the Only Sane Man? Is he in agreement with what Chris does? Do either one have a crush on the other?
First generation
Justin - A plain out narcissisticJerkass from the get-go, or was he really a Nice Guy at the start of the series, but Took a Level in Jerkass after Heather got him voted off? Several fanfic writers love exploring the latter.
Is Heather's friendship with Cody and Harold genuine? Unlike with most other contestants where it's made clear Heather doesn't care for them, it is made somewhat ambiguous with them. In the World Tour finale, they are the only ones to initially support her against Alejandro. Cody's reasoning being that Heather was pretty nice to him, and Harold does it due to his beef with Alejandro. On one hand, she has stated that she sees them as mere potential alliance partners, and has openly insulted or mocked them on various occasions. However, she has shown a degree of respect for them at one point or another, such as when she admired Harold's num-yo skills, or being inspired by Cody's words when he told her that she is the "good" guy.
Was Courtney always a Bitch in Sheep's Clothing or was it Duncan's influence on her? Proof for the latter could be that in World Tour, in the half Duncan wasn't in the game, she seemed to be back into her Island characterization.
Is Courtney a whiny Jerkass who puts herself before everyone else or is she a regular girl who let the competition get to her head? Did she plan to eliminate Gwen in All-Stars because she wanted to win, or because she still had doubts about Gwen wanting to stay her friend?
Was Courtney actually attracted to Alejandro and Scott, or were they Replacement Goldfish for Duncan? A massive appeal of flirting with Alejandro was how Duncan seemed to be jealous, after all. Also, despite her flirtation with Scott, she's relieved in "Suckers Punched" that she doesn't have to worry about Gwen "stealing" Scott because of how gross Scott is, which opens up the possibility that she dated him because she's that afraid of being cheated on again, so she went for somebody nobody else would date.
Izzy's insanity makes it difficult to tell which elements of her history and personality are true and which are fabricated, one example being her ambiguous romantic history with Justin, which could either have some backing (which Justin would likely want to forget) or could be entirely something she made up. There's also ambiguity as to whether her personas Kaleidoscope and Explosivo are just her play-acting or indicative of some Split Personality thing; while it's nowhere near as obvious as Mike and his personalities in later seasons, the super-smart and rational Brainzilla does seem to indicate that Izzy's brain can be shaken into another consciousness. The fact she gets a career as an actor during Celebrity Manhunt gives more credence to the idea that she's playing up her craziness for the cameras.
Heck it's questionable if she's even crazy in the first place or just pulling a very convincing Obfuscating Insanity act. This video goes in depth on how it could be the latter.
Is Gwen secretly just as bad as Heather and Courtney, it's kinda fitting that Heather's Establishing Character Moment in "Island" was getting out of the boat complaining and insulting everyone, and in the series finale Gwen does the exact same thing. Also she's shown to be quite superficial as she frequently clings to snap judgements about people in spite evidence that their different to how they present themselves and warnings from people who know that person better than her. She continually held honest mistakes and misunderstandings over Trent's head throughout their relationship. In "World Tour" she showed no remorse for Courtney whatsoever, only feeling sad about how her reputation was being tarnished and only really caring about perusing a relationship with Duncan, yet in "All Stars" after her relationship with Duncan had grown stale she suddenly apparently felt a great deal of remorse for what she did despite steadfastly refusing to admit to it and wanted to be best friends with Courtney, who she'd never made a genuine attempt to get to know as a person and spent their whole friendship willfully ignoring her demonstrating the very behavior she never misses an opportunity to insult Heather for. Even her adamant refusal to forgive Heather for her behavior in "Island" comes off as hypocritical considering Heather has shown a softer side many times since then, while Gwen has been perfectly willing to give people who have done much worse than her such as Courtney and Alejandro the benifit of the doubt. It could be argued that all three of them have been gradually becoming each other as the series progressed since Heather went through the exact same character arc in "World Tour" as Gwen did in "Island".
Was Heather simply being a Tsundere with Alejandro or was she actually annoyed with him and he sexual harassed his way into her head?
Alternatively he could have slowly warmed his way into her heart with his charm and villainous nature? Considering in All-Stars, he does a lot less sexual harassing and seems to be on more equal footing with her in the relationship.
While it's most likely she meant the kiss and confession, it's unclear whether Heather intended the Groin Attack right after. Did Heather immediately know what Alejandro was doing and planned ahead or was she just as caught up in the moment as he was and only did it as she remembered her priorities last second?
Some theories theorize Sierra doesn't really love Cody and that she either loves the idea of him or simply wants to be in a relationship.
Did Lindsay actually take a gigantic level in dumbass in All-Stars, or was she only playing dumb because she was tired of the show and knew that it would get her voted off first?
Did Scott really undergo Villain Decay in All-Stars, or was he always a dumb Country Boy who decided to be crueler than usual in his time on Revenge of the Island as part of a game show persona? Or perhaps he was some combination of the two: a decent, but intelligent guy, who received brain damage when Fang messed him up.
Third generation
Was Dave a self-centered Entitled Bastard whose Sanity Slippage was a result of a well-deserved rejection at long last, or was he a not-entirely-sympathetic Dogged Nice Guy who was outraged at his (proven mutual) crush's reveal of having a boyfriend, whose Face–Heel Turn ironically proved he did have morals?
Topher's character page on the show's wiki brings up a question regarding his Chris-obsession and eventual attempt to take his job: did Topher legitimately admire Chris or was he just stroking his ego as to lower his guard?
Was Scarlett face palming at the reveal of the Twin Switch because it was so obvious she's upset the others didn't see it or is it because she didn't know and was frustrated with herself despite it being so obvious.
Sugar calling out to Leonard as she's being eliminated. Was it a sign that she has a bit of a crush on him or did she wanted him as a Morality Pet so that she could have someone to boss around?
Fourth generation
Considering Axel's similarities to Shawn and the fact that she owns a zombie standee modeled after him, was he an inspiration for her to become a Crazy Survivalist? Or was she already one to begin with and simply respects his skills as a fellow survivalist? Alternatively, were their similarities purely coincidental and was the standee just a reference for the viewers' sake, meaning she isn't Shawn's Hero-Worshipper and potentially doesn't even know about him, assuming she hasn't watched all seasons?
How genuine is Bowie's friendship with Emma? He does offer her an ear when she rants about Chase and is friendly with her overall, but his nature as The Strategist means he could also be acting as what she needs so he'll have an ally in his corner. When Emma breaks them off, he seems to show more interest in keeping her vote than her friendship.
During the scene where Damien is touched over Millie and Priya's reconciliation, Caleb can be shown visibly moving up in the background, but his face wasn't shown. Was Caleb also touched by Millie and Priya's reconciliation as well or was it something else?
Is Millie Freudian Excuse to why she was so lonely due to a disability or are Millie's parents very overprotective and homeschooled her (since Millie does not feel comfortable talking about her family life)?
Priya, in spite of having been subjected to extreme stage parents as a child who trained her non stop for a future season of Total Drama and want her to do the reality TV circuit instead getting an actual career, is shown to still care about them and is pissed at Millie for writing mean things about them. Does she genuinely not realize how horrible her parents are or is she in denial for whatever reason?
Some of Ripper's idiocy seems to be genuine, but given that he has a strategic side that wasn't fully explored, does he actually fake most of his stupidity so he doesn't look like a nerd?
Scary Girl reveals in the fourth episode of the second season that she lives in a funeral home. Did she choose to live there on her own because she was a Nightmare Fetishist to begin with? Or did she live there from birth because her family owns it and living there was what contributed to her becoming so unhinged?
goes in depth on how it could be the latter.