All of it is history from the initial revolution. Khomenei, the original (not the one killed a month ago), was a high-ranking Shi'a priest. He drafted a theocra

All of it is history from the initial revolution. Khomenei, the original (not the one killed a month ago), was a high-ranking Shi'a priest. He drafted a theocratic constitution, that was mostly agreed upon, except a few caveats that gave the Mollah (high-rank priests) their own police forces and basically supremacy of the religious over the civil government (this was to make coups harder). Their police forces, the IRGC, slowly gained more and more power and tied themselves to the Khomenei. The original Khomenei died, but someone from his clan was also a Mollah, and was designed next leader. That created a tension: was he the leader because he was part of the clan, it because he was a Mollah? In any case, the clan and the IRGC gained more and more power, and the last transition was a soft coup. The new leader doesn't have the rank of a Mollah, and even though he was a priest, there's now way he was selected without pressure on the others. See it at the pope not being a bishop first. The MEK were Marxists revolutionary in 79 who were shafted by the new constitution and oppose the Mollahs since then (and probably the reason why Khomenei and Shi'a priests who were exiles in Irak were 'convinced' by Saddam Hussein, a US puppet at the time, to go to Iran take control of the revolution).