There are few anecdotes about him, and pictures, at least ones that have appeared publicly, are scarce. The younger Khamenei operates behind an elaborate security structure, an overlapping world that stretches from Iran's Revolutionary Guards to the motorcycle-riding Basiji. That accumulation of control was used to outflank reformists such as Hashemi Rafsanjani and Hossein Ali Montazeri, revered figures of the Islamic Revolution who years ago had questioned the senior Khamenei's qualifications as supreme leader. The violence that has erupted over the last week -- state media have reported that 10 to 19 people have died -- were in part the...