Okay. This might sound stupid but I seriously don't understand why Cas leaves Dean. As in the infamous crypt scene where Dean confessed his feelings. And then again where he leaves to hunt Lucifer directly after he tells Mary he thinks he doesn't belong. Also when Dean is talking to Cas about his mother living in the bunker and how awkward it is and Cas just says something and hangs up on him. I mean why!? Why!? Doesnt Cas love Dean?!! 😭😭😭😫😫😫😑
Hey! Apologies for getting to this so late - Christmas has turned into the freaking apocalypse around here (but, then again, that’s sort of our Christmas family tradition, so I feel both resentful and weirdly reassured and thank God for raw cookie dough).
So, first things first - Cas does love Dean. Cas loves Dean very much. In fact, Cas loves Dean so much he can’t focus on anything else, which means he can’t function, which means he’s useless and broken, because angels are not people - as far as we know, they were never supposed to have free will and were created to obey orders and carry out missions, so if they aren’t capable of doing that - then what? If your laptop stopped working and started doing its own random thing instead (and, I don’t know, set fire to the whole house just to save one beetle trapped against a window), you wouldn’t keep it around, right? You’d bring it back to the factory and have it reset.
(Or, as it happened in this amazing fic, you’d fall in love with it and then hate yourself, because, yeah, that’s not normal until it is.)
So, no - if Cas walks away, it’s not because he doesn’t love Dean.
Mostly, Cas walks away because he doesn’t feel like he deserves to be there (and Dean’s understated signals are not strong enough for him to pick up). In his mind, he hardly deserves to exist, let alone to live a life of diner food and Star Wars marathons with the Winchesters in the Bunker. I mean, Cas failed as an angel - apparently, he fucked up every single mission he was ever given, had to be tortured into obedience way too many times to count, and yet he kept fucking up and now his brothers hate him and even God himself didn’t bother to acknowledge him in any way. And Cas also failed as a human, so much so even Dean sent him away. He failed as a hunter, he failed as a guardian angel, he failed as a surrogate father (look at Claire and how her family was torn apart and destroyed). And, well, he failed as a friend, because he couldn’t protect and keep safe those people he loves most in the world.
(This is not the way I see it, obviously, but from what we know, it’s definitely how Cas feels.)
And, well - some of it is all Cas - we know that ‘too much heart’ was always his problem, after all - but lately, every single ‘wrong’ choice Cas has made, he made because of Dean, from rebelling against Heaven to hurting Sam to letting loose an ancient and terrifying force whose only purpose was to swallow the world whole. Because Cas is learning feelings from Dean, so it doesn’t matter if the actual responsibilities are much harder to pin down - Cas will think it’s his fault, because without him Sam would never have managed to save his brother and the correct course of action in that situation was Death’s, not Cas’: Dean sent to space somehow, or to some alternate dimension of primordial forests and loneliness, and Sam - Cas could have erased Dean form Sam’s mind, just like he erased him from Lisa’s and Ben’s.
(As for his own mind - yeah.)
But, of course, Cas couldn’t do it. And those people who died? On him. Lucifer out of the Cage? On him. And you could argue many of Cas’ ‘mistakes’ are now old history, but in my opinion - we are human - we are designed to forget and overcome and heal - our pain blurs, bad memories fade, mistakes are excused and buried. But Cas - Cas is a machine, and all the things he’s done, all the choices he’s made, every single angel he killed, every person who died on his watch, every single flower which withered and wilted and got extinct - also that one Tongtianlong limosus who stumbled and fell and drowned in a bog, his wings flailing uselessly, his mind a black music of urgency and panic - all those creatures Cas had to kill or couldn’t save - they’re all right there, and Cas can’t let go, and he doesn’t know how to get over it -
(“We were supposed to be their shepherds.”)
- and it plain hurts. And Dean is not helping, because every damn step of the way, Dean wordlessly confirms that yeah, this is completely normal, man, and welcome to the fucking club (feeling guilty about everything, giving up on the stuff you want, because you were never supposed to get it; always putting others first).
So, to answer your questions more specifically -