Chapter Text
Dean wakes up with a woman in his bed.
Which is not, in itself, alarming—except he'd gone to sleep with Cas next to him, mussed and half-naked and pleasantly spent; waking up alone would've been surprising enough, but he's got no fuckin' idea how Cas could've slipped out and this woman crept in without his waking up for at least part of it.
She stirs, turns to him with a yawn, and the eyes she opens are a shade of blue he'd recognize anywhere. "Good morning, Dean," she says in a rich contralto, and her eyes widen; her hand flies to her throat, probes the absence of an Adam's apple. She sits up, frowning in that unmistakable way, and slides her hand down to clutch a bare breast.
"Dean," says Cas—because that's who it is, even though that's impossible—"something happened to me overnight."
"Yeah, I got that," Dean says. He props himself up on an elbow, which has the unfortunate effect of putting...Cas's...boobs right in his line of sight. Okay, it's not unfortunate at all, as they're pretty damn nice to look at; still, it feels impolite. His eyes are up there, he chides himself, and he drags his gaze back to Cas's face. While his jaw is narrower, and there's an unsettling lack of stubble, the eyes and mouth are the same, and his dark hair's still short, giving him the pixie-ish look that Dean doesn't usually go for.
Today, though, is obviously unusual.
Cas, of course, is unfazed by his nudity, squeezing and poking his newly feminine flesh. He throws the covers off to investigate further; he's wearing the boxers he fell asleep in, tight over rounded hips and thighs. When Cas slips a hand between his legs, Dean reaches his breaking point, and he springs out of bed like a jack-in-the-box.
"Hey, we should—let's go wake up Sam, I think this is all hands on deck for research, don't you?" He heads for his dresser swiftly, turning his back on his topless boyfriend. Girlfriend? Cas.
"Yes, you're right. This must be a spell of some kind," Cas says. His voice is an octave higher than usual, but that's not saying much; it's low, rumbly, and Dean has a weird flashback to being a kid, ogling Jessica Rabbit's impossible curves while Kathleen Turner purred "I'm not bad, I'm just drawn that way."
"A spell! Yeah! Sam can help, hit the books, figure this shit out." Dean tugs on his jeans, touching his cock as little as possible while he zips up his fly. "You'll need a shirt," he says as he grabs one for himself. There's one at the back of the drawer that shrunk in the wash, maybe that'll fit Cas's new body.
But when he risks a peek, Cas is already dressed in the same button-down and slacks he had on last night, and they're not a bad fit. Apparently he didn't lose any height, and he was pretty lean before; so while the pants cling to his ass and he has to roll up his sleeves a little, he looks good.
So good, in fact, that it doesn't help the situation in Dean's pants one bit, and it's a heroic effort not to just walk over there and take those clothes back off.
*******
Sam is understandably nonplussed, and his gaze moves down Cas's curves a little too slowly for Dean's taste. "It's gotta be a spell, right? Fuckin' witches?" says Dean, stepping between them.
"That's one possibility," Sam says, and he gets that excited I'm-on-the-case look he gets, the one that heralds a long, woodcut-heavy day of research. "What were you doing before it happened?"
"Performing fellatio on Dean," says Cas.
"Sleeping," Dean says loudly into the awkward pause. "You were, uh, you were definitely a dude when you fell asleep."
"Well, it doesn't seem likely that either of those—activities would cause the transformation on their own. I meant more, what were you up to yesterday? Weren't you in one of the artifact rooms?"
Yeah, because they'd gone in there to make out under the guise of being helpful. "I don't think we touched anything," Dean replies, but oh, wait. "No, we knocked over a box, and this stick thing fell out. We put it back, though, right where we found it."
"Stick thing," Sam says thoughtfully. "Can you show me?"
*******
It takes some embarrassing moments of re-creation ("No, Dean, you spun us around and pushed me up against that shelf"), but they find the box and take it back to the library. The object isn't a stick so much as a short staff, with two carved snakes winding around it and wings fanning out from the top. "Oh, that explains it," says Sam. "It's a caduceus."
"A what? I don't get it," says Dean, glowering at the thing like it's gonna leap out and attack him.
"Caduceus," Sam repeats. "It gets used as a medical symbol a lot, but that's actually confusing it with the rod of Asclepius, which only has one snake. This is the rod of Hermes, but even before that, it belonged to Tiresias."
"Tiresias? The blind guy from the Odyssey?"
"Hey, ten points to Gryffindor!" says Sam, clapping him on the shoulder. "Yeah, same dude. And he gave Oedipus the bad news about his mom, too. But before any of that, the lore says he saw two snakes having sex, and he hit them with his staff—Hera got mad and turned him into a woman. So I guess that's what happened to Cas, he must've touched it accidentally when you picked up the box."
He's shining with triumph, but Dean doesn't feel it. "Did he change back?"
"He did. Seven years later."
*******
For once, Dean doesn't mind the hours stuck in the library, poring over old-ass books to find some way to fix things without having to wait for the better part of a decade. Cas is right there with them, but he doesn't seem to feel the urgency that Dean does—eons as a genderless wavelength have left him pretty indifferent to the exact nature of his physical form.
Dean's having some trouble dealing. He's just barely accepted that he's in love with and having sex with a man, still working on understanding that part of him, that it's been there all along and is nothing to be ashamed of—it feels like cheating to have Cas turn into a chick. He's plenty hot, Dean can totally picture them together (has been picturing it all day in a Technicolor blur of mental images), but—how can he still be bi if he's dating a girl? Was all that soul-searching, that bravery he summoned up to kiss Cas for the first time, for nothing?
He's still brooding when they finally call it a night; they've got a few leads for shortcuts, but nothing definite yet. Cas follows him into their room as usual, strips back down to boxers and climbs into bed. Dean hesitates after taking off his shoes, can't help but stare at Cas's boobs, think about what's under the unflattering underwear.
"What's wrong?" asks Cas.
"Can't you sleep in a shirt?" Dean manages to say. "I can't—I don't think you know how distracting you're being right now."
"I have an idea," says Cas indignantly. "I'm attracted to women as well, just like you. I know you're aroused looking at me."
"Then why won't you cover up?"
Cas rolls his eyes. "I'm trying to seduce you, Dean. I want to have sex while I'm like this."
Dean can't speak, and Cas continues calmly, "I came across an interesting tidbit while reading about Tiresias's experiences. It seems he was called to settle an argument between Zeus and Hera, about whether men or women felt more sexual pleasure. And he told them, 'of ten parts a man enjoys one only.'" Cas grins. "I'd like to test that theory."