Here are some darker fics. They may involve non con or dubious consent and violence, or simply a rather twisted scenario. If you don't like sexual violence, be careful to look over the story warnings first. Click below if you want to sample the dark side of the Snarry.
Abstract Concept, Cinammon Twists Author's Warnings: Chan, non-con, rather dark
Amanuensis
Hypocritic Oath Author's Summary: Harry's not well. Neither is Snape. Author's Warnings: Non-con. Prostitution. Voyeurism by way of third-party OMC. Sloppy seconds.
A Spell to Turn Tigers Into Butter Read review here (note: the link for this and the next story are to the author's opening page. Click through to her HP story title list to get the particular story link.)
And Just Plain Wrong Author's Summary: Voldemort has won, and Hogwarts is the Death Eaters' twisted playground. Author's Warning: I've wanted to do the "Twisted Hogwarts" evilfic for some time. Yeah, this one's nasty.
Amy (also known as Swtalmnd), The Intricacies of Expectation (Author's web-site. Click through links to find story.) Author's Summary: Harry makes Snape an offer and gets something rather different than what he's expecting. Author's Warnings: Bondage, Highly dubious consent, CBT, Object Penetration
Atrata, Hits The Ground Author's Summary: Snape comes back from a Death Eater meeting, and his Issues manifest in a decidedly ugly way. Author's Warnings: Very dark. Implied noncon, torture.
Cluegirl
Let All Mortal Flesh Keep Silent (Scroll down page.) HP/SS, HP/LM, HP/PP, HP/Other Author's Warning: BSDM, Violence, Slavery, Breathplay, Bloodplay, Character Death, and much Angst.
GMTH, And Miles To Go Before I Sleep Author's Warnings: This is a dark fic and contains elements of non-consensual sex (i.e., rape), forced prostitution, abuse, violence, bondage, and public sex. There is also a graphic piece of fanart at the top of the page which is absolutely NOT WORKSAFE.
Isis, Be Careful What You Wish For Author's Summary: Harry decides he wants Snape -- and then changes his mind. Maybe. Author's Warnings: Dubious consent.
Isolde, Childe Harry To The Dark Tower Came Author's Summary: A risky potion is botched and, acting as an unstable portkey, transports Harry and Snape back in time to a seedy Wizarding village (before it became Hogsmeade) where they must assume a Master/slave relationship while trying to escape. Author's Warnings: Bloodplay; breathplay.
Jellybean Slash, Dreams and Reality Author's Summary: Somehow he had lost control of himself, of his mind, and the filthy thoughts and images that seemed so real overtook him entirely, erasing rather than blurring the line between dreams and reality. Author's Warnings: Non-con, BDSM, D/s.
Kai, Give, And It Shall Be Given Unto You (Scroll down.) (Various pairings) Author's Summary: "Surprises are foolish things. The pleasure is not enhanced, and the inconvenience is often considerable." Author's Warnings: Broken!Sub!Snape, DarkishLord!Dom!Harry, 2nd person narrative, fluid time-line, melodrama and various cliches.
Lady Bastet, Paying the Price for the Sins of His Father Author's Summary: In the beginning of Harry's first year at Hogwarts, he learns that Snape really doesn't like him, and that he takes great pleasure in hurting him. Author's Warnings: Chan (sex with a minor), rape, non-con.
Laura the Auror, Savagely Still Author's Warnings: NonCon, rape, chan, underage, angst, teh trauma, The Gay, bondage, Slytherin sex toys, obliviation, Legilimency, Dark magic, clichés, Snape is Darker here than in canon (I reckon) and Darker than I usually see him.
Lesyeuxverts, His Lily Author's Summary: Body and breath and soul, she is his, married to him, just as she always should have been. Author's Warnings: dub-con, potion use, EWE
Lithrael, Hint, Hint Locked at Pornish Pixies, please ask to be friended. Author's summary: post-HBP, Harry gets Snape at his mercy, but screws it up. Author's warnings: Slash, rape, snark
Mouse, Corvus Fallere or here. Author's Summary: How long do you fight when you've already lost? Harry, Ron, and Hermione must survive in a world where all is not what it seems; but what it seems is unbearable. Author's Warnings: Not so much as a AU as a what if futurefic. Started BEFORE book 5, so that's where it diverges from cannon. BDSM, a lot. Slavery. Nastiness. No main character death, though minor character death is mentioned in passing.
Penumbra, Necessary Surrogates (note: this is the first in a series of four short stories.) Author's Summary: "The straight set of his shoulders is almost painful to see when I know he is the Atlas that holds me aloft."
Rae Whit,
The Scarecrow Author's Summary: Be careful what you wish for. Author's Warnings: Highlight at the story page, if you wish to know.
Fallen Far From the Tree Albus Severus/Snape, Harry/Snape Author's Warnings: Infidelity, bondage, non-con Summary: Caught between two generations of Potters—literally—Snape discovers that his namesake is cut from a different cloth than his father. Author's Notes: There is no chan in this story. There is, however, per my recipient's request, post-war Headmaster Snape. I'll leave it up to you to decide if he's pervy; I do think he's ugly. Thank you, J., for beta reading. And snogs to the Mods for giving us a reason to smut in the spring.
Rex Luscus, Contrapasso Author's Summary:contrapasso, n. the ironic cosmological law ensuring that "the punishment fits the crime." Author's Warnings: Non-con, torture (more psychological than violent), mentions of character death (canon and non-canon), HBP spoilers.
Rube, I Saw You With Me Author's Summary: Snape faces his worst fears, unaware he has an audience.
Rushlight
A Fracture Of The Mind's Eye Author's Summary: A tragedy at the end of Harry's seventh year makes him redefine his perception of reality. Author's Warnings: Rape, violence
Sine Que Non 767, Detention and Release Author's Summary: The age-old excuse still holds good. "Detention, Mr. Potter." Author's Warnings:: M/M slash, sub/dom themes, non-consensual, violence.
TC Regan and Sophie Richard, An Unconventional Relationship (scroll down page to get story links) Authors' Summary: Harry's time at the Dursley's has left him with some rather odd quirks that only Snape can help him work out.
Tangle Foot, And Dagger Author's Summary and Warnings: This is a dark little non-con written for no particular reason. It’s your typical ‘Voldemort has taken over, Harry-and-the-Death-Eaters’ type of thing. Mostly it’s Harry/Snape, in a gruesome sort of way.
Thamiris, Dragon-Blind (note: chan, as well) Author's note: PWP, dark, dirty, and dubiously consensual. Author's warnings: Harry wants Snape to be kinder, but Snape obliges on his own terms. Set during PoA.