Callisto Hime

Callisto Hime is the username of a fanfiction authoress on several sites, including Deviant ART and Fanfiction.Net. She took Fire Emblem (the Akaneia and Elibe series) and The Legend of Zelda and wrote two fairly popular fanfics enjoyed by Zelda fans and not so enjoyed by Fire Emblem Fans due to more or less rewriting or ignoring Fire Emblem canon due to only knowing about the series from Super Smash Bros.

Her first notable work was a fanfiction called Time Cannot Erase, which starts just after the ending to Ocarina of Time. Ganon is sealed, and Link and Zelda begin to grow apart over time. Link travels the world for six years while Zelda remains in Hyrule. However, one day a prince from a nearby kingdom of Akaneia arrives in Hyrule...

Tropes associated with her work:

 * Always Chaotic Evil: Unlike the Fire Emblem Akaneia and Elibe games where all nations are presented equally, in this fanfic all other Akaneia and Elibe nations are simply evil and receive no focus.
 * Automaton Horses: Uncompromisingly averted. Link and team's ride from Hyrule to Aritia is long and tiring. It completely wears out the horses quickly, and they have to swap horses at locations where Link has made loyal friends from previous adventures.
 * The Bro Code: Marth's attraction to Zelda proves disastrous to his friendship with Link, eventually leading to Link
 * Cassandra Truth: Zelda has to go through this.
 * Childhood Friend Romance: Link with Zelda and Roy with Elice.
 * Crossover Ship: In-Universe. Marth/Zelda, Roy/Elice.
 * Out of Character: It's pretty clear she has absolutely no idea or doesn't care how the Fire Emblem characters she uses are supposed to act and behave. Same deal with the nations and world.
 * Dark Fics
 * Dragon Rider:  Also wyrm riders, which is close enough.
 * Fantastic Racism
 * Florence Nightingale Effect: Marth to Zelda.
 * Half-Human Hybrid:  This is probably not that surprising to anyone who knows Fire Emblem.
 * Intercontinuity Crossover/Crossover: In addition to the obvious Zelda/Fire Emblem blend, non-Fire Emblem fans might not be aware that Roy and Marth never meet in canon. They come from separate games in the series.
 * Interspecies Romance: There is a half-dragon who is a byproduct of this that goes on to have his own romance with a human.
 * Joker Immunity:  was not enough to kill
 * Love Triangle: Marth <> Zelda. Link > Zelda. Zelda and Elice > Link. Roy > Elice. Manasa >
 * My God, What Have I Done? In his last moments,  regrets the way he treated her. It does not keep him from dying however, so all he can do is
 * Mythology Gag:
 * There's a scene in the second story of Link fighting a Wolfos which alludes to Wolf Link. It's probably either a Mythology Gag or faux/foreshadowing that Wolf Link is eventually going to make an appearance.
 * Link has a knack for randomly finding rubies in all sorts of weird places, in a reference to how you can find money by cutting up grass and breaking pots in the Zelda games.
 * Zelda writes a book called The Legend Of Zelda.
 * Original Character: Manasa debuts in the second fic and eventually gets paired up with one of the canon characters.
 * Parental Abandonment
 * Parental Neglect: Zelda's dad is not the best.
 * Pregnant Badass:
 * Rape as Backstory/Rape as Drama: It's implied that "Navarre" raped Manasa. He certainly abused her.
 * Shown Their Work: As an experienced equestrian, Callisto Hime writes horse riding very realistically.
 * Slap Slap Kiss: The Roy/Elice ship is this.
 * Transplanted Character Fics/InNameOnly: Other then the names of some of the characters, it has otherwise no connection to Fire Emblem and might as well be a different story altogether.
 * What the Hell, Hero?: