Settings
Concepts/Plots
Kidnapper/Kidnapped
Angel/Demon
Pirates/Navy
Nerd/Jock
Outcast/Jock
Outcast/Nerd
Vampire/Victim
Vampire/Slayer
Werewolf/Human
Brother/Brother
Ghost/Hauntee
Stalker/Stalkee
Blackmailer/Blackmailed
Elf/Dark Elf
Human/Elf
Alien/Abductee
Human/Monster
Zombie/Human
Warlock/familiar
Enemy/Enemy
Straight male/Straight male
Servant/Master
Prince/Guard
Prince/Stableboy
Prince/Bandit
Submissive top/Dominant bottom
Teacher/Student
Hunter/Hunted
Vampire/Werewolf
Super Villian/Super Hero
Gay male/Straight male
Boss/Employee
Employee/Employee
Male/His shadow
Male/Not so imaginary friend
Pairings
Plots/Settings
The Brother's Grimm
Post Apocalyptic
Ship/plane crash on deserted island
Future or space
Medieval renaissance
Paranormal or haunted
Neanderthal times
Present day or slice of life
Slave pens of the colliseum
A masquerade ball/party
Bootcamp
Warzone/battlefield
Alternate reality
School/academy/college
Asylum
Urban jungle
Baldur's Gate series: Siblings, both born of the god of murder, one could be good the other evil. They fight for the throne, etc.
The Walking Dead: Co-op fanfiction Darryl/Glenn
Harry Potter: Co-op fanfiction/AU
Teen Wolf: Co-op fanfiction/AU
Repeat gloryhole encounters
Sex with strangers/masked lovers
Fairy tales with a twist/AU