This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Total Drama Letterz
When Quana is eliminated, Spider tries to eliminate himself to save his girlfriend. It doesn't work, and Quana is sent off, with Spider sadly watching her until the boat disappears into the horizion...
In the next episode, Barney breaks his leg during the Donkey Kong challenge...which leads to him being eliminated from the competition. Before he is eliminated, he and Lavender say their farewells.
Vinnie sacrificing himself so that Uzuri can stay in the competition.
When Nakia verbally attacked VayVay of her bisexuality, it hurt her so much, she broke down in tears.
Jimmy getting himself eliminated because he felt like it was time for him to go.
Lankston's home life isn't pleasant either. Guy's got a chip on his shoulders for a REASON.
At the beginning of TDL 3, Jimmy's entire family DIES. On his 11th birthday. His scene ends with Eleanor comforting him.
Nakia's mother, Annabelle, dying from a heart attack due to the stress of seeing what her daughter did and went through in TDL 1 and TDL 2. It affects Nakia so badly, she goes to place flowers over her grave at the beginning of TDL 3, and is clearly still not over it.
The scene where Kim tells her backstory to Steve. Just... the whole scene. Seeing how the horrible trauma Kim experienced as barely a teenager evolve until it reached a boiling point in TDL 2 is really articulated in this scene, and it certainly helps the reader to understand Kim more as a character. To add, it's also one of the only moments in TDL 3 where Steve is NOT happy-go-lucky.