some dragon rider gender headcanons, in no particular order:
(note: these are primarily for characters from the first book, as that’s the one i’m most familiar with; i may make a second post for griffin’s feather-specific characters at some point in the future.)
enchanted creatures tend to default to either agender, or whatever their creator assigns them; with time and exposure to one set of Gender Concepts or another, they may eventually go with one that they like instead
the ravens are never referred to with gendered language, and largely have either never bothered to experiment with gender or haven’t done so in a way that translates over to human languages
nettlebrand’s a binary dude in human terms, is still Genders because he’s an enchanted agender-by-default creature who pointed at one and went ‘that’s mine now’
if the homunculi had lived to be exposed to Genders(tm) over time, most of them would have been somewhere on the nb spectrum; they’d have used a range of different pronouns, instead of the alchemist’s blanket assignment of he/him. some of them would have been transfeminine with she/her pronouns, they/them pronouns, or sticking with he/him anyway because it’s what they’re used to and they don’t mind it.
twigleg is vaguely-guy-flavored agender, and only that much because he just goes with it when people gender him male. it started with the alchemist designating all the homunculi male (which, y’know, obviously he’s not going to dare go against that), and then with nettlebrand being so enamored with Being Male that he projects it onto his servant as well. now he just kind of reflects what people expect him to be, and has only started to get more comfortable with his own internal perception of his gender after meeting ben and getting acquainted with his genderfeels.
speaking of which: ben is actually vaguely shrugs about gender, and doesn’t have any particular attachment to it. it’s one reason he’s drawn to (sapient) fabulous creatures--especially before he realizes he’s nb--just because in general they’re so much less stifling and binary about gender than humans usually are. it’s also a big reason he and twigleg connect to each other so much, as mentioned above.
guinevere is a trans girl who was sure about it very early on. the greenblooms happily put their full support behind her without ever looking back
silver dragons are all nonbinary by human standards; instead of lacking gender at all, though, their gender spectrum is just Alien to humans and vice versa. they have both nb and ‘’’binary’’’ trans folks, just by dragon standards and not ours.
firedrake and maia are both the dragon equivalent of binary trans (although they have more than two of the genders we would consider ‘binary,’ so it’s more like quaternary or thereabouts). slatebeard is Dragon Cis(tm)
gravelbeard and petrosius are the token human-standard cis. gilbert and lola are also cis, but they’re valid
sorrel is just the knuckles comic. what’s a pronoun
more to come if i forgot anyone, whoops