Laconic: The glue that holds the bad guys together.
Villains, as a rule, aren't good at working together. Evil tends towards selfishness, whether it's the cackingly-mad Card-Carrying Villain or the Well-Intentioned Extremist who insists that only his way is the right way. Therefore, a group of villain usually needs at least one teammate able to make the group thick as thieves. That's the role of the Dark Heart.
The Dark Heart is the evil equivalent of The Heart; the core of the team, the one who smooths over personality conflicts and reminds everyone of what keeps them together. They might be the team's Morality Chain, keeping them from being too evil, or they could just be trying to direct the evil outward, away from other team members. Very often a woman and possibly the Token Good Teammate, but most times the Dark Heart is fully supportive of her teammates' ways, and she's much less likely to perform a High-Heel–Face Turn than a more standard villainess.
Not to be confused with The Man Behind the Man, who manipulates the villains to attain a personal goal, or with the Greater-Scope Villain who often rules over the villains but isn't concerned with internal conflicts as long as they don't interfere with his own agenda.
