The Substitute.

We all know by heart what happened with the Goblet of Fire.

Let's imagine that the awful chunk of magic involved in the well-known trickery triggers...something, revealing cruel truths and twisted destinies. Well, A twisted destiny, the Substitute's.
Unsurprisingly, this rather old (2008) story by BajaB, an evil twist of the good'ol "Wrong BWL" plot, is titled "The Substitute".
(Complete, 6 chapters, 35K words)