buffy
I've come to the conclusion that a fundamental difference between the way I tend to view fiction and the way the Buffy fandom does/did while looking through old posts is that I think both Angel and Buffy often whimped out when it came to making things truly dark. See: Wes in season three and how pretty much everyone lost their characterization to alienate him.
Like if I wanted to do a truly dark season six of Buffy? Would have killed Dawn in season five. Would have had Buffy watch as her baby sister willingly walked towards her own death to save the world. Buffy would have followed through on the threat of giving up Slaying.
I'd have season six about Buffy embracing her rage at the world. I'd have her sick of living in a world that would give her sister, give her fourteen years worth of memories loving her, only to be forced to watch her die. I'd have her be angry that she had to kill Angel for real. I'd have her lash out and push everyone away. I'd relate that to Willow's control issues, Xander's intimacy issues and Giles darker tendencies.
Like I'd have a scene where Willow offers to get rid of the memories of Dawn to help the pain and have Buffy go ice cold and tell her if she ever mentioned something like that again... and not even voice the threat before walking off.
I'd have Willow's control issues go so far she accidentally kills Tara. I'd have Xander push Anya away more and more until she asked what was his problem and then have her walk from him until he can grow a spine and actually get out of the basement that he still acts like he lives in. I'd have Giles struggling to connect with Buffy and lash out at her when he can't give her any answers and make them say things to each other they really don't mean.
I'd have like a moment after darkening up Buffy properly where she watches a vampire kill an innocent and not give a damn. I'd have her have mutually abusive sex with Spike because it's about the only thing that makes her feel anything. And when she tells him that, he thinks it's a sign of their true love and encourages her to continue to fuck off the world. She'll break it off when fucking Spike stops making her feel anything.
And at that point, I'd have Buffy find out about Willow's careful plot to destroy the world to end all pain forever. I'd have Buffy catch her and having Willow be so dark punch her in the face as she tries to stop her. I'd have Xander walk in after Willow knocked her out and well have the same basic ending of season six where he saves her from herself by opening up his heart to intimacy again. I'd have Spike try and get rid of his chip in the end, only to be cursed with a soul. I'd give implications that Giles plotted out Willow's decent to destroying the world after Tara died in a last desperate attempt to fix things.
Season seven? Would be about the characters relearning how to trust and open up to each other and heal and deal with all the mistakes they've made. Because, despite what modern TV is trying to tell me, healing characters is just as interesting as breaking characters.