People can't blame 8-4/Localisation for Faye's character. Last time I checked, this was her character in the JP original version. Heck, this was the time that people "wished" for her to be "localised." I remember seeing people at SerenesForest saying they hope she's better in the "localised" version.
I sincerely want to know what made IS consider this and even go full-out on this. You had Cordelia and Oboro who were characters with crushes and you had Tharja, Camilla, and to an extent Jakob, with the Obsession deal, but despite their crush/obsession, they had other character traits, could restrain their obsession and weren't jerks to everyone(even Jakob had people he did not chew out on first encounter, specifically Sakura, Azura, Hinoka, Nyx and especially Mozu, easily one of his best Supports).
Heck, even if they wanted a character similar to the above characters.....what exactly prompted them? Heck, to a sense, what was the point? Alm and Celica were destined to S-rank and there's no character like Robin or Corrin. What exactly prompted this action? Heck, what's up with only 2 supports? Why does it feel like she was a last-minute entry?
THAT BEING SAID, I would like to point out and how ironic it seems that she has 10x more development in Fire Emblem Heroes than she does in her entry game. And no, I am not joking. Despite the fact that all of her talking quotes are about Alm, here is her Confession.
I understand that it's not hard to involve Player Bias in a game with a Player Insert. Yet this is probably one of the few times that Player Bias is actually helping the character than hurting. It shows that she can actually change, that this Confession Quote should actually be something in her game, yet the opportunity is not there. The chance is never given.