The webcomic I was referring to is called Sister Claire. You may have heard of it, I think it used to be fairly well known back in the day. No idea what state the comic is in now though, it's been around 3 years since I stopped reading it, I think.

Anyway, the comic had a couple characters that were based on characters the artist was a fan of. One was Olga, who was based on Helga from Disney's Atlantis: The Lost Empire. Another was Oscar, who was based on a character of the same name from an anime called The Rose of Versailles. Oscar and Olga were pretty clearly originally just intended to be "jokey" side characters, but they both got upgraded to main characters later on. Oscar especially had a really small role in the story before the artist went back and started changing shit.

Oscar was the one who was later made MtF, and I'm pretty sure I know why. I've never watched The Rose of Versailles personally, but I do know a little bit about it. In the anime, Oscar was an actual woman who was raised as a boy by her father because he wanted a son so badly. I think the artist of Sister Claire just thought they were being sooooo clever, to have an MtF character be based on a female character who was raised as a boy. As if to say that Oscar in Sister Claire and MtFs in general are just like the Oscar from The Rose of Versailles: girls who were wrongfully raised as boys and "assigned male" by someone else.