Fan pairing are pretty much exactly how they sound. Pairing up different charcters. My favorite is so unusual.. Batman/Sealand. Don't ask. I have written a fanfic with them already. Yesh, Sealand from hetalia, i no i no..
NOOOOOOOO!!!!!! Obviously Howl and Turnip (Prince Justin) are meant to be together. D:<<< Don't even get me started on how much I hate Sophie.
Also, Ike/Marth from Fire Emblem. As evidenced by some wonderful photos in SSBB.
That's all i can think of right now.
EDIT; That first line was meant to be a quote. oops.