Oh, Canon.

Canon. One of my favorite fanfiction genres. Actually, it is my absolute favorite. The reason why: these stories focus on the characters we first fell in love with. 
If you are out of bounce with this term here is the definition, exclusively from Wikipedia (because we all love it!):


Canon refers to the "official" source material upon which fan fiction can be based. In recent years, some fandoms have engaged in lengthy debate over what is or is not "canon", usually due to multiple writers in various media creating contradictory source material... It is important to note that something that is regarded as "canon" is regarded as being essentially a verifiable fact in the given fandom. Details as complex as the laws of physics in a given story universe or as minute as how a character's name is meant to be spelled can be referred to as "canon" details, so long as they are specifically shown or otherwise directly revealed in the source material; this includes character behavior as well, though debate over what can or cannot be considered "canon behavior" is often a point of contention in fandom... In short, "canon" in the context of fanfiction is both the accepted "official" material itself, and a concept or detail promoted by the original work and/or in accepted "official" material.


l'm not so sure that I accept canon as 'official material, though, but the stuff written is fantastic (most of it). Some examples of the work:
Triangles With Linear Qualities- 
Jacob doesn't even like geometry.


I liked this one, since it is in third person and that it is set place in New Moon (my favorite book). Bella and Jake are taking a break from being 'irresponsible' and doing homework. Jacob uses the triangles he is studying for math as a metaphor for his relationship with Bella. 


Numb- 
We know Bella tore her stereo out of her truck...this is her story of that day.


This one-shot killed me. Seriously, I was so upset when I read it. Music is a connection that Edward and Bella have and when he leaves during New Moon, all that is gone. Every reminder of him, taken away, broken, like the stereo.


Whole- 
After centuries of waiting, the Cullen family is finally complete. Rosalie observes as the last piece of their puzzle finally slots into place.

This was so canon. It showed Rosalie's reaction to Renesmee perfectly. While Rose thinks that Nessie is hers, she needs to face the truth. She isn't her daughter and Rose will have to accept that. 


If you'd like to read more like this, there is an awesome C2 Community called All Canon Twilight