Okay, playing this is easy. The person above you says the name of two totally unrelated characters from HP and than the person below creates an original couple name for them and then says two other characters and then the person below them repeats. For example:

cuteypuffgirl:
Harry Potter + Ginny Weasley

randomuser45:

Harry + Ginny = Hinny

Ron + Hermione

personbelowu78:

Ron + Hermione = Hermioron

Neville + (insert name here)

etc etc...

Get it? Okay I'll start:

Bill + Fleur