May I offer a headcnon?
Blind Zephyr
Thoughts, both solo and with Mountain below. Nothing explicit, but implied horny things in the distance.
Not completely blind, but their vessel has some unfixable eye impairment that limits sight and progressively worsens. That's why they were a band ghoul for such a brief period, their eyesight tanked after the tour ended. Eventually they end up functionally blind, just able to make out shapes and colors but nothing close to detail.
They adapt fairly well, but they do end up relying on the others a bit more at first. Especially Mountain, who's easiest to pick out in a crowd. Zephyr isn't a huge fan of siblings, and they've made the mistake of assuming a sister is Dew three times too many, so it's easier to look for the blob of beige that they know to be Mountain’s antlers.
Mountain doesn't mind.
He doesn't baby Zephyr the way Aether sometimes does, and he doesn't use kid gloves the way Dew and Ifrit tend to. Mountain is easy, honest. Helpful without being overbearing, doesn't presume to do things that Zephyr certainly can on their own. He waits for them to ask, and Zephyr is always silently appreciative.
They wish they could see more of his handsome face, though. Wish they could count the freckles speckled over his nose and cheeks for the hundredth time, that they could admire the squared off edges of his pupils and that one auburn streak in his hair.
But their memory will have to suffice - though Mountain never objects to letting Zephyr touch his face when they need a reminder. To bring the ridge of his brow and the hump on his nose back into sharper relief in their head.
Touching that, of course, never stops at Mountain's face.
Zephyr insists on facing him whenever they fall into bed, regardless of who's doing what. Mountain assured them that he will always look into their eyes, even if they cant see him, and Zephyr believes him.
After, Mountain will read to them. That's the one thing Zephyr misses more than any other, even more than their keys - being able to squirrel themself away into a nook in the library with a thermos of tea and a good book. But Mountain's voice is lovely, and the way his chest vibrates under Zephyr's ear is so soothing. Like this, they can forget their loss for a minute.
Mountain traces shapes into their skin while he reads, and Zephyr memorizes every one - hearts and stars and Z's and M's and nonsensical squiggles. Sometimes Zephyr will ask how a character's name is spelled, and Mountain will write it on their back while he spells it out loud.
Zephyr always drifts off faster than they intend to, but it's unavoidable. Mountain will finish out his chapter and they'll settle down, face to face, with Zephyr's hand over Mountain's heart. Just a reminder. Zephyr knows they don't have to, but they always thank Mountain for everything. He'll shush them, always, kiss their cheek, and for a second Zephyr will SWEAR they can see him.
They sleep the best those nights.