Fanfiction/fan art/anything coming from fans of the Harry Potter series that has something to do with members of the Malfoy family being "together," whether it is in an intimate situation, or just romantically, or both.
Pairings include Draco Malfoy/Narcissa Malfoy, Draco Malfoy/Lucius Malfoy, and Draco Malfoy/Lucius Malfoy/Narcissa Malfoy.
Lucius Malfoy/Narcissa Malfoy is not considered Malfoycest because (a) They are already married and (b) They are not direct blood relatives.
Malfoycest is my guilty pleasure.
"I love Draco and Narcissa together, they're so cute!"
"Lucius and Narcissa is my favorite Malfoycest pairing!"
"...but Lucius and Narcissa isn't Malfoycest."