Being Human, George/Mitchell, ashes to ashes dust to dust
Lost, Kate/Sayid, knowledge is power
Merlin/SPN, Uther/John, a man's home is his castle
You can leave as many prompts as you'd like as long as they're one per comment, and you can even write your own.
If nothing here takes your fancy, then head over to the Lonely Prompts index and grab some inspiration there.