i don’t and i’ve searched through like the entire dean/cas/meg tag on ao3 (there is NOTHING good it ALL sucks) BUT i can tell you that there is a secret good season nine that lives in my head (concocted in conjunction with @lesbiansamwinchester) where meg lives and they complete the trials at the end of season eight with meg as the demon they’re curing and sam dies BUT sam comes back as a ghost tied to the impala but doesn’t show himself to dean so dean doesn’t know, but he DOES show himself to kevin and kevin ends up stealing the impala and joyriding around the united states having a coming of age arc while sam just kinda. hangs out and tries to mentor him semi-successfully. BUT it does get them out of the bunker.
meanwhile in the bunker, dean is a depressed wreck because sam is dead and he can’t even sell his soul about it because hell is locked, meg is a wreck because she’s been a demon for thousands of years but now she’s a human so she has a “conscience” and she has to reckon with all her “atrocities” and also because meg has always been kind of a wreck she just puts it aside to follow orders or to survive but now there aren’t any orders and she’s not in any danger so she’s slowly going insane having to “face” her own “problems” and “trauma,” cas is a wreck because, well, he’s human now and also the angels fell and it’s his fault, but also like. he’s doing the best of any of them, because 1) he’s not being forced to interact with society he’s just hanging out in the bunker with his friends who are used to him and know how to interact with him and accept him, he is part of a community (even if it is only a community of three) and he belongs there, 2) Dean Is Being Nice To Him Right Now, always a prime factor in cas’ mental health, and 3) dean and meg both need him to take care of them emotionally and that’s something he can do, he’s good at being therapyfriend. (they also to an extent need him to care for them physically and he’s worse at that but he approaches it with gusto and he learns. this is normally a role dean takes on but he is too fucked up even for that during the early parts of this arc; one of the signs that he’s slowly healing is that he starts cooking for cas and meg).
anyway one of the things that happens is that meg and cas are sleeping together, and it’s very much a no feelings, fuckbuddies thing (although they are both aware that meg is deeply in love with him and simply do not talk about it or admit they are aware of it out of deference to her pride. you know. normal shit) BUT dean’s ideas about sex are Diseased and he thinks meg and cas are Dating Seriously, With Intent To Marry And Everything, (because cas is innocent and pure and could NEVER just be having no strings attached sex, that’s for evil irredeemable man disease havers like dean) and he is just. so mad about it. That Demon Skank Is Manipulating Cas With Her Feminine Wiles, Just Like She Did To Sam (cut to meg crying in her room because cas will never love her back while cas obliviously tries to make everyone a nice breakfast because he loves his friends <3!) like dean is so mad. he’s sublimating his [REDACTED CAS RELATED FEELINGS] into protectiveness.
now into this mix you throw in one (1) adrenaline and belligerent sexual tension filled post-hunt hookup between meg and dean. cas stayed home at the bunker on this one so dean and meg are alone which like never happens and they do some violence together and then they end up fucking afterwards because of the adrenaline rush and because the belligerent sexual tension they have is off the chain. this pushes dean into a complete meltdown because he’s like i fucked my best friend’s girl, the ultimate betrayal, how can i ever redeem myself oh god, oh woe is me, meanwhile when they get back to the bunker and dean goes and hides in his room, meg goes up to cas and is like by the way i fucked dean, wanna hear about it? and cas is like Yes Of Course Please Tell Me Every Detail I Am Very Intrigued and then they have deeply weird sex while cas updates his fantasies about what dean would be like as a lover.
anyway normally i’m a “i enjoy megstiel because i love the tragedy of cas is in love with dean, but can’t have him, so he’ll use meg as a substitute / meg is in love with cas, but she can’t have him emotionally, so she’ll use fucking him as a substitute” person but actually i think they could work something out and be in a triad where everyone is emotionally satisfied. like i think meg being there might actually help cas get with dean, (”if you’re so concerned about protecting cas’ honor from my feminine wiles, you’ll just have to join us, dean-o” and then slowly lifting veils of plausible deniability until dean has to admit that he has feelings for cas), and once it’s less of an eternal pining situation with dean, cas might be able to genuinely give something back to meg, emotionally speaking.
also if they’re both fucking cas, dean and meg’s dynamic is...... incredible. it’s a special little prickly but ride or die friendship that i’ve invented completely in my brain but i love. they’re the definition of vitriolic best buds. also they have sex but only when they’re housewifing around the bunker waiting for cas to get home like a nineteen fifties husband. (when i say housewifing i mean dean is obsessively cleaning the kitchen and making dinner and meg is sitting on the couch eating chips).
i know this isn’t quite the angst that you asked for but it’s what i have. in my brain.
