Release - Dean/Castiel. Bottom!Castiel. First time. Dean is affected by an unusual sex curse that makes him want take a mate.
Open Communication - Dean/Castiel. Top!Castiel. Est relationship. Castiel usually the bottom and doesn’t want to top. Dean learns it’s because angels knot.
Take You As You Are - Dean/Castiel. Bottom!Castiel. First Time. Dean gets bitten by a werewolf. Castiel wants to prove to Dean it doesn’t matter to him what form Dean is in. Contains sentient bestiality (sex between full-wolf-form-Dean/angel-human-vessel-Cas)
Instinct - Dean/Castiel. Top!Cas. An epic AU with werecat-shifter!Cas and werewolf-shifter!Dean. Does NOT contain knotting though. Multichapter.
Look Into My Eyes and I Own You - Dean/Castiel. Top!Cas. Dean gets turned into a werewolf and then goes into heat and starts humping everything like a horny dog. Enter bamf!Cas.
Frozen Inside - Dean/Castiel. Bottom!Cas, skinwalker AU. Doesn’t contain any knotting until the very end. Really good story though. Multichapter.
Found - Dean/Castiel. Top!Castiel. Wolf AU, no human forms just wolf/wolf. (Almost forgot to add my own fic on here… XD)
Pack Rites - Top!Cas. Wolf AU, but it’s Castiel/Jensen. No human-forms, just wolf/wolf.
Saint Elmo’s Fire - Top!Castiel. Dragon!Dean/Angel!Castiel – Rimming, knotting, wing!kink, bdsm, collaring, courting customs, frottage, Also contains explicit Dragon!Jared/Dragon!Jensen, & Dragon!Sam/Angel!Gabriel, but you could always skim past those parts if the other pairings bother you since its basically pwp.
Pretty Baby - Top!Misha. Werecat!Misha/Human!Jensen.
Lakota Falls - Dean/Castiel. Top!Cas. Werewolf AU. Multichapter
Obsession Becomes You - Dean/Castiel.Top!Cas. Heavey D/S. Godstiel/slave-Dean.
Burning Up for You - Top!Misha. Misha/Jensen. They are still actors on spn, but in an alpha/beta/omega universe.
Jailbait - Top!Misha. Misha/Jensen. Prison AU that takes place in an alpha/beta/omega society.