Out of curiosity, what's your personal preference for the fic actor characterization poll you posted? Thanks!
Well my first instinct was to say I do like it when fics incorporate the actor into the character...
(Talking specifically about Bucky, I was thinking about the RL-example of how they put him in Bucharest, in CACW, because SebStan is Romanian, so he could speak Romanian in the scene. I thought it was neat!
So I do like it when fic-Bucky has specific Romanian or Eastern European heritage, a la the actor, because it lampshades this very obvious aspect of SebStan's appearance... which it would be odd to ignore, given the context of the Brooklyn which Bucky grew up in (with rampant antisemitism targeted at EE Jews, where looking EE would have an impact on others' perception of him and his perception of the world.
Owing to-- I guess you could call it colorism? shadeism? --back then, this Bucky would've grown up, for example, watching actors who resemble him being typecast as villains and monsters -- Little Caesar, Frankenstein, etc. Boris Karloff wasn't even EE!) You could also read Bucky being Romanian as a callback to Jewish Romanian Stan Lee, as well.)
...But then I realised I'm actually in the 'depends' camp.
Depends on the character and depends what the actor-trait is.
Those Bucky examples fit the character, but while sometimes the actor-trait adds depth, or addresses a plot hole, sometimes it's just OOC for the character.
I don't mind, eg. people incorporating physical description that very obviously references the actor playing the character, or adding in Cevans' boob-grab laugh into Steve's characterisation, because neither of those things affect Steve's personality. But adding in Cevans traits (or traits of other characters he has played) which don't match Steve's personality ... that does bother me.
For example: even despite Steve's drastically different background, Cevans' tattoos could actually work, on Steve, because it's a counter-cultural thing (compatible with his politics), and Steve grew up in a rough area of Brooklyn with loadsa tattooed sailors around, plus if Steve was a poor amateur artist then tattooing would be one of the few professions he could incorporate that into!
But making Steve (het-romance avoiding, demi- or ace- readable Steve) into a (how can I put this diplomatically? let's go with-) ladykiller, a la Cevans in his slooty era? That just isn't Steve, to me!
And IMO that goes for Bucky, too.
SebStan has multiple 'sad gay spoiled lil rich boy' roles under his belt, and I just can't vibe with AU fics that make Bucky one, because he's nothing like that... I feel like you could swap in a baby Howard Stark without changing anything, and that's usually a sign of poor characterisation in my book.
(Plus, from a shippy perspective, Bucky's upbringing (facilitating defence of underdogs against bullies) + experience of adversity + shared life experiences are all vital to his personality and to what makes him attractive to Steve... so cutting out all those Bucky traits just to put OtherSebStanCharacter's Traits in their place doesn't work, for me! I'm left wondering '...but why would Steve like this guy?')
Another example: SebStan's appealingly awkward theatre-nerd™ clumsiness?
Yeah, it's adorkable, but it makes no damn sense for a Bucky who's supposed to be this former-ladykiller *ahem* dancer sniper supersoldier, etc!
So that's where I am on it.
Hope that answers the question for you, Anon!