I have suspected for some time that it its not nearly as random as it may at first seem.
At the risk of sounding cliched: love. For someone in particular, or for friends, or family. It would be simple to allow that love to fuel my darkness - and I cannot be certain it will not someday become an issue - but those I care for benefit more from my continued control than they would from the destruction I could cause. For the moment, that is enough.