Largest Black Hole Found in constellation Cancer

This thing tips the scale at 18 billion times more massive then our sun. It is also orbited by another smaller black hole as well as powering a quasar. Now that is one interesting system.

This particular quasar has a regularly pulsing light signal with two major
pulses every 12 years. The first two pulses were observed in the year 1994-1995,
and the first one of the next set in 2005. The observations helped astronomers
refine their computer models, predicting the next pulse would come on Sept. 13,
2007.

I wonder why this quasar is so regular like this? A massive pulse every 12 years is pretty odd. You would figure something like energy falling into a black hole would more random and chaotic and send out bursts with no pattern. But this quasar seems to shoot the energy out every 12 years. Strange stuff.