Supernatural's characters tend to get tortured, but few have had it worse than Adam Winchester (Jake Abel), being left to rot in Hell by his own brothers. According to Sam and Dean Winchester, nothing is more important than family, especially each other. They've literally died for each other more than once, and have also risked everything to save each other multiple times too. No matter the hurdle, Sam and Dean are willing to clear it if that means keeping their family intact, or at least intact as possible.
Yet for some reason, those family values never applied to their half-brother Adam. Sure, they didn't grow up with him, and he was the product of their dad John having a fling with a nurse that they weren't aware of, but blood is blood. Or at least that's the rule for everyone not named Adam Winchester, aka Adam Milligan. When it comes to him, apparently the ties of family aren't really that big a deal to Sam and Dean.
Not appearing at all since Supernatural's season 5 finale, Adam was left to twist in the wind - or more accurately fire - for nearly a full decade. His absence even became a kind of morbid running gag among fans, one which actually made it into the show proper a few times. After all he's been through, Adam deserves better.
Supernatural: Why Adam Winchester Deserves a Happy Ending
At the end of "Swan Song," Supernatural's season 5 finale, Sam - possessed by Lucifer - and Adam - possessed by Michael - both end up trapped inside Lucifer's cage in Hell. Sam is shown back on Earth at the very end of the episode, and season 6 explains that Castiel rescued him, but couldn't retrieve his soul. Death later retrieves that. Yet, outside of a cursory attempt by Dean to persuade Death to save Adam too, Sam and Dean seemingly did absolutely nothing to try and save their brother from a decade - or more, time moves differently in Hell - of torment, stuck in the cage with not only Michael but Lucifer, at least for quite a few years. Sure, Adam and Michael eventually reached an understanding, but Sam and Dean had no way of knowing that.
The fact that Adam's brothers left him to literally rot in Hell is inexcusable, and entirely out of character for Sam and Dean, who as Adam even points out to Michael, are usually on the right side of things. Yet, they have no real explanation for why they abandoned him, outside of being busy with other stuff. While Adam's now free from Hell, he still has to share his body with an archangel, who despite their deal, can take over his body at any time. Adam has been through enough at this point, and perhaps more than anyone else in the Supernatural universe, deserves a happy ending. Not only does he deserve a real apology from both Sam and Dean, he also needs to be released from Michael's grip, and allowed to reunite with his mother in Heaven. Anything less just isn't fair.