@Fwelin  
I always thought of a head canon being something that a individual believes is relevant to a show, book, comic, movie or game. Regardless of if their head canon conflicts with show canon or not.  
Like if I have a head canon that includes Queen Chrysalis as a second wife for Shining Armor that Princess Cadance is totally okay with. The shows canon clearly states that Queen Chrysalis does not live with Shining Armor. But do I still want to believe that Shining Armor has two wives that are constantly fighting each other for his love and affection? Sure!

@Ping_chan  
I mean, they kind of do. Headcanons are a fan’s interpretations or desires about a story that refer to events or states that are neither supported by the story nor disproved by them. Something that breaks canon isn’t a legitimate headcanon.
 
Headcanons having to be compatible with the story is why people often talk about them being ruined when they get disproven. For example, I used to have a headcanon that Celestia and Luna were given the reigns of Equestria when they defeated Discord, but Princess Twilight Sparkle disproved it when it showed them already having their modern crowns when they turned Discord to stone.

@Background Pony #3F07  
It’s just a head canon, it doesn’t have to be logical or make sense. :v

Cute

@Background Pony #879A  
It actually wouldn’t, since Daring Do’s design was shown on the cover of the book in Read it and Sleep, before Rainbow was a fan.

@Ping_chan  
That would explain why Daring Do is basically a Rainbow Dash recolor with a pith helmet and a khaki shirt.

@Ping_chan
 
@infinita est lux Solis  
We already know she wrote self-insert fanfics for The Wonderbolts.

@Ping_chan  
Seems pretty unlikely that she would have portrayed herself so critically in Daring Don’t.

@Ping_chan  
I actually kinda like that idea.

Yep, this is my head canon for Miss Dashie… In fact I’ll expand upon that head canon by suggesting that Daring Do is not really real in the show and A. K. Yearling is simply just a fiction author.  
Every episode featuring Rainbow Dash and Daring Do together is just one of Rainbow Dashes self insert fan fictions. :p

Only 98% of them are self-inserts.