Reddit mentions of Understanding Video Games: The Essential Introduction

The developers and the gaming community in general needs to have better language to designate types of player characters. I think our expectations get messed up because our terms are muddled.

For my part, I consider basically three types of player characters: avatars, actor characters, and role-playing characters (terminology borrowed from this textbook, and that's honestly the only part of the book that's remotely useful). Avatars are literally just the player in virtual space; they have no place in narrative games and largely function as representation for the player among other players. Actor characters are fully-scripted, set-in-stone characters whom the player happens to control during gameplay segments (so most FE lords-- Marth, Eirika, Alm, etc.-- would fall into this category). And then in between those two you've got a spectrum of role-playing characters where the player has varying degrees of control over their person and narrative actions (whether in their imagination, as with silent protagonists, or in the actual mechanics of the game). It's possible to build a functioning story around a role-playing character, but it requires tact and understanding. I would say it also only works well with a tacit understanding that the player is separating themselves from their character to a certain extent. They are, in fact, playing a role. They should not be coddled.

I think IS has been writing for actor characters in FE games, letting the player change their gender and hair color, marketing them like they're role-playing characters and their choices matter, and then putting bumpers on the narrative to avoid hurting the player's ego. It's pretty confused IMO. But I also think Nintendo's getting more of a handle on this sort of thing. I'm looking at stuff like Xenoblade going from a customizable player character back to an actor one, Zelda finally settling on just calling Link Link... it seems like they're starting to get either that they can write better stories with actor characters or that role-playing characters stretch their resources too thin without offering the player the payoff of meaningful choice (which would require, guess what, more resources). FE Switch may be a good outing for them to experiment with meaningful choice, but they really gotta commit to it and get over any "avatar-ism" with the character. Otherwise I'd be fine with an MU in a very minor role. I'd recommend planning for supports with every character, but parceling them out among different character "types," so that only 4-6 are available per playthrough. This creates organic character development and a sense of choice without forcing the MU on characters unnaturally or getting into massively branching paths.