@EddersCPFC  
Yup, it was Night Light. Supposedly during a rocky time in his marriage which he made up after and left Trixie and her mother behind. (bastard)

@Red Cedar  
In that fanfic, which parent did they share? I’m guessing Night Light because Trixie does have similar colours to him.

@EddersCPFC  
I read one good fanfic where Trixie was Twilight’s half-sister, and acted the way she did out of jealousy. There’s no canon evidence.

@EddersCPFC  
That’s just a crazy headcanon that rarely sees much use anymore.

Why do so many people seriously think Trixie is Twilight’s sister? If fine for a joke, but if you’re gonna take it seriously then it makes you look like an idiot.

I’ll take Trixie being antagonist over whatever your crazy plans are in order to “save” her… She was pretty much redeemed in the Magic Duel episode from Season 3 despite the ending seemed somewhat rushed. And the comics made her more humble and sympathetic than she is on the TV show. She could be an ally to the mane 6, helping them fight a villain or something, or the mane 6 help her a good reputation in Equestria, because there’s not a lot of ponies who likes her very much or her magic shows, then learn a lesson about friendship. But that’s just me…
 
“Trixie Wants To Becomes Twilight’s Sister” My reaction was like :…What??

Twilight’s sister? Fucking what? Please, tell me you’re not being serious.

This could be a good microgame for Warioware.

Sorry, I read that as “Shave Trixie!”  
/Not serious.

Save Trixie! (For the firing squad.)

She’s Becomes A Background Protagonist.

Yes I Am, Chi.

From what?
 
Your crazy plans for her?