Foreshadowing/Fan Works

Examples of Foreshadowing in Fan Works include:

The fact that Aeon Natum Engel is (somehow) darker than the original is probably something to do with the sheer amount of foreshadowing.
Kyon mentions his uncle is called Keichii in one early chapter of Kyon: Big Damn Hero. Later on, he ends up in Hinamizawa for Golden Week, staying with said uncle.
Happens in every other scene in Hammered Down. When you get to the climax, it's like everything just decided to go boom.
Occurs twice in the Portal 2 fanfic Test Of Humanity. First is when Wheatley gets stuck in a garbage chute after trying to find a way to get into the lab and save Chell.. He later gets stuck in an exhaust pipe (he's too fat to fit all the way through) causing it to explode). The second time is when Wheatley is overwhelmed with guilt after watching 2001: A Space Odyssey and begins comparing himself to HAL. During the climax GLaDOS tortures Wheatley by playing the film but replaces HAL's dialog with Wheatley's evil speeches from the games.
In the The OC fanfic AVDC, Summer hits on Alex early on in the story. Later in the story she ends up in a relationship with her Non Rival Anna
The author of the Mega Crossover fan comic Roommates loves to do this, and is actually good in it. If something is in the comic it will be important eventually. Like: Why on earth is the Erlkönig on the monitors of Heaven and Hell together with Jareth and Jadis? They are family. Or This highly literal example.
In The Tainted Grimoire, there is a lot of these.
Three big examples in Pokémon: Storm Clouds:
- When exploring the ruins beneath Saffron City, Nightshade comments that Pokemon Tower was thought to have been built by the same civilization. The artifacts in the Tower prove crucial in returning Dan and Missy home.
- The phrase "pokemon are made of stronger stuff than humans" is thrown about a great deal in the early chapters. This foreshadows Missy's survival of the apparently-lethal wound inflicted on her at the story's end.
- At one point, Masque responds to Giovanni's directives with a smug "You cannot control a marionette with only one string." This comment, seemingly mere insubordination, actually confirms in a big way that Masque is the real danger and manipulating Giovanni. It even receives a direct Call Back when Masque reveals his true nature.