Transformation, Animagus and Creature!fic There are a number of good stories where either Snape or Harry appear as magical creatures, Animagi, or, possibly, sitting room furniture.
Alchemia Dent and Bugland •A Bittersweet Potion, R for violence, 81,000 words Warnings: (highlight for spoilers) *Murder or Attempt, Suicide or Attempt, Violence, unusual magical theory* Summary:During Harry's 5th Year at Hogworts, he receives a highly sought after Gift- but will it be more trouble than its worth? Snape (to his horror) learns he trusts Harry. Draco attracts trouble. And as usual, Dumbledore knows more than he lets on. And how is absinthe involved.
Amorette •Learning to Uncurl, G, 3,997 words. (gen) Warnings: (highlight for spoilers) *humor* Summary:A decade after hostilities are over, Harry finds his Animagus form to be terribly relaxing and since he thinks Snape needs to learn to relax, suggests Snape learn to be an animal as well. Surprises ensue.
Cluegirl •Disenchanted, NC-17, 20,253 words. Warnings: (Chan, 16) (highlight for spoilers) *Chan - 16, D/s, mild CBT, and orgasm denial, sorta-kinda-but-not-really bestiality, allusions to child abuse.* Summary:Sent to Privet Drive to intercede in a domestic dispute, Severus finds that Harry Potter is not quite feeling himself.
Dementor Delta •Parseltongue-Tied, NC-17, 16,158 words. Warnings: (highlight for spoilers) *Animagus Bestiality, romance* Summary:Harry Potter makes friends with one of nature's shy creatures.
Drachenmina •Fly in the Ointment, R, 10,400 words. Read review here. Warnings: (highlight for spoilers) *Clichés, crack, and cringe-makingly contrived cuss-words.* Prompt:Snape is developing a potion so that vampires can go out in sunlight and visits the castle of a vampire clan for research. Harry is there as a fledgling who develops a fancy for him. Snape is not amused.
•A Most Impractical Cat, NC-17, 12,400 words. Warnings: (highlight for spoilers) *Mention of het, (very) mild BDSM, bestiality and the poetry of TS Eliot.* Summary:AU. During the horcrux hunt, Harry goes to Malfoy Manor in his guise as a cat to try and find Helga Hufflepuff’s cup. Things do not go according to plan.
Eeyore9990 •Grabbing a Bite (Even If It's Not a Sandwich) PG-13, 1,400 words. (Chan, 17) Locked community, please Content/Warnings: (highlight for spoilers) *Chan: Takes place at the end of DH, so Harry is still 17. Vampire!Snape* Summary:Harry just wanted a sandwich and some sleep. He (eventually) gets some sleep.
Elmyraemilie •One For Sorrow, Two For Joy, NC-17, 21,595 words. Warning(s): (highlight for spoilers) *None* Prompt: Severus has Adult Onset Animagus Syndrome; it's very dangerous. Healer!Harry is the Animagus specialist at St Mungos. Review: You can find a review for "One For Sorrow, Two For Joy" here.
Entrenous88/Entrenous •The Bite and the Cure, NC-17, 10,900 words. Warnings: (highlight for spoilers) *Explicit sex. Life-threatening situations* Summary:When a grave danger threatens Harry Potter's life, Severus Snape offers the only cure.
Femme •Exegesis, NC-17, 49,150 words. Read review here. Warnings: (highlight for spoilers) *Minor character death, religious/theological elements* Summary:Every culture has their tales regarding creatures of the night.
Gingertart •Getting Familiar, NC-17, 15,000 words. Warnings: (Harry is 17 in this story) (highlight for spoilers) *Underage (Harry is 17), EWE, voyeurism.* Summary:Snape has watched over Potter for so long that nothing from poisonous snakes and assassins to amorous doppelgangers can stop him. Eventually he's going to figure out why.
•Nine Days Wonder, NC-17, 8,100 words. Warnings: (highlight for spoilers) *Mpreg, crack, sex magic, and drastic over-eating.* Summary:AU in which Dumbledore died from the curse before Draco could attempt to kill him, the trio didn't run off on a camping trip, Ron makes good on his early promise of being a brilliant strategist and Snape gets his usual shit deal from fate. He does get heroically shagged, though.
Igtow •A Bird In Hand, PG-13, 1,290 words. Warnings: (highlight for spoilers) *Humor, fluff, Animagus* Summary:Harry never can stay out of trouble and discovers something about Snidgets the--mes-mes-messy way.
Josan •Severus and the Crup, NC-17, 36,484 words. Warnings: (highlight for spoilers) *Hurt/comfort, Animagus, drama, angst* Summary:What happens when a man meets a dog.
Merri-Todd Webster •Give and Take, NC-17, 6,595 words. Warnings: (highlight for spoilers) *Unusual Sexual Situation* Summary:Harry learns that life and death are both a matter of give and take.
Perfica •Aqua Fresca, NC-17, 86,491 words. Warnings: (highlight for spoilers) *Bloodplay/Breathplay* Summary:Set in an alternative reality which veers from canon after OotP, and where Harry is over eighteen and attending Hogwarts. Harry witnesses Severus suffering under an unusual curse. Both of them struggle to come to terms with the new intimacy that springs up between them because of the vision.
Predatrix •Occasional Table, NC-17, 11,693 words. Warnings: (highlight for spoilers) *Explicit sex. Life-threatening situations.* Summary:Severus attempts the Animagus transformation with intereresting results. Instead of an animal, he ends up transfigured into inanimate objects. Funny how many of those objects end up in a young Gryffindor's hands...and mouth...
Ravenna C Tan •The Company You Keep, NC-17, 9,969 words. Read review here Warnings: (highlight for spoilers) *Ambiguous Consent, Disturbing content, Rape/NonCon, Sex. Brief flashbacks to sex with Voldemort's captives, mentions of non-con and rape. Dubious consent Snape/Harry.* Summary:The war is over. Severus Snape wants to be left alone. Draco wants Snape. Snape decides a stray cat is a better companion that a Malfoy, given what he learned about both Malfoy and Potter in the days after Voldemort had captured Harry.
Resonant/Resonant8 •The Familiar, NC-17, 5,539 words. Read review here See illustration by Morskaya here Warnings: (highlight for spoilers) *Animal transformation, humor, hurt/comfort* Summary:A potion goes awry.
Rhaegal •A Mutually Beneficial Arrangement, R, 9,984 words. Warnings: (highlight for spoilers) *Vampire!Snape.* Summary:Harry inadvertently stumbles upon Snape's biggest secret.
Spinner •Blind as a Bat Series, PG-13, 87,695 words. Warnings: (highlight for spoilers) *Slash/slashy scenes, vampirism, foreign words and phrases, ill-advised acrobatics, discussion of child abuse, insinuation of child sexual abuse, explosions, cat death, pirates, various random acts of violence, humor, non-Snarry pairings* Summary:Harry is having a rotten summer between his fifth and sixth years. Once back at Hogwarts, the school year doesn’t get any better. He’s experiencing precognitive dreams, and he’s starting to sense things about people when he touches their personal items. If that’s not bad enough, the new Dark Arts instructor appears to fancy him, and Professor Snape is being nice to him. It’s enough to make anyone a bit jumpy.
As luck would have it, Severus Snape is also having a rotten year. His long-estranged, presumed-dead wife has surfaced to ask him for a divorce. The new Dark Arts instructor clearly has a fancy for Harry, and Snape is trying to protect the stupid boy from her. He finds that protecting Harry might mean he has to be kind to him. *ick*
The Con Cept (Also known as Abstract Concept and Starry Gazer) •Felinated, PG-13, 17,800 words. Warnings: (highlight for spoilers) *None.* Summary:A potions accident leaves Snape as a cat until who-knows-when. Harry’s already got his hands full when a prankster starts sabotaging the rebuilding of Hogwarts. But what if it’s not just a prank?
Thesewarmstars •The Plant, NC-17, 8,145 words. Content/Warnings: (highlight for spoilers) *None* Summary:Neville turns over a plant to Harry and explains that the plant told him it was Severus Snape. Harry probably should’ve listened. Review: You can find a review for The Plant here.
Tira Nog •Nocturne, NC-17, 94,840 words. Warnings: (highlight for spoilers) *Homicide/Murder, Hurt/Comfort, Violence/Torture* Summary:Auror Harry Potter learns a startling secret about his former Potions teacher.
Ziasudra •Tachycineta Carmina, NC-17, 1,908 words. Warnings: (highlight for spoilers) *Ambiguous Consent, slavery, angst, romance, happy ending* Summary:"Snape liked birds. He liked birds because they could fly. To him, each flap of the wings meant defiance—challenging gravity, demonstrating freedom—and Snape valued freedom."