Spike is trying not to muster up any sympathy for Discord. Discord warped the Elements themselves, changing most of the Bearers permanently into twisted versions of themselves and forcing the pony who raised Spike, Twilight Sparkle, to change herself into something cruel and cold. He killed Discord for doing this, took a sledgehammer to his statue, but Discord came back. Now Spike is trying to remind himself that he has no sympathy for Discord at all as Twilight is torturing him in her experiments...
...until Discord reveals that the one Spike killed is still dead, and he, the one who's being tortured, is from another universe and never committed the specific crimes Spike hates him for.
The story is a sequel to "Discord in Hell (Not Literally)" and probably makes little sense if you don't read that first. No on-screen torture. Like Spike himself, we just hear the screams and then see Spike cleaning up afterward. But if you're sensitive to gore, or implications of rape, skip this fic.
There is now a series page: Elements of Opposition
Discord travels to an alternate timeline so he can have fun without angering his new friends, and ends up in a horrible situation.
Twilight Sparkle, element of Magic and Order, reports to Princess Celestia on her findings regarding the apparent re-emergence of Discord.
Spike is trying not to muster up any sympathy for Discord.
The Mane 6, plus Spike, go to a universe where their doppelgangers have been turned evil, to rescue Discord.