Thugdere is when someone (typically a female character, though it can in some cases be applied to a male) often mistreats their lover, often physically or emotionally harming them, but can also be quite affectionate toward them. The "thugness" is often a way they hide their sweet, caring, and loving side, which they may often think makes them look weak or foolish. Not to be confused with tsundere, kuudere, or yandere.
"Alice is really thugdere. She's always going from treating Mike like crap to being all sweet on him."
by A_Laser_Eyed_Dragon February 03, 2014