I’m presuming crossover doesn’t count here, but rather a true fusion verse fic? Not really…probably the closest I’ve come is my one Jingle Bells Burn Notice song fic but I really don’t think that’s what you are going for.
13 – Do you prefer canon or fanon when you write?
It depends on the fandom. Fanon, in and of itself, is problematic because you have to identify it and not all the fandom will know or buy it. And is different than writing a true AU of a character or what have you. But then again, we also have source materials that are deliberately obtuse about telling us certain things for ages and ages *side eyes Supernatural, Teen Wolf* resulting in you having to start making up your own stories about certain characters like Mary Winchester’s family or what the hell is Sheriff Stilinski’s first name. And some of those become widely enough used that there are certain levels of fanon about them *Tom Stilinski* while others no one ever completely agrees upon and the show eventually catches up and Josses your universe *Mary Campbell from the Campbell hunting family*
Other times we get left enough vagueness that everyone comes up with their own theory, and the different settings/tropes themselves are fanon but everyone handles them differently – Shepherd Book as an Operative for example.
So yeah, it depends. I like to be able to use canon for the timeline or different things, but unless all you write is episodes, missing moment fics, or introspective pieces, at some point you have to pull away from canon to say X was off doing Y here.
Has writing fanfic for a fandom changed the way you see some or even all of the original source material?
I don’t know about changed my opinion of the source the material. Writing from different characters POV has changed my opinion of different characters to an extent. But not really the source material