This person is never anyone expected or overly important. They are simply the crowned one, the head of the hive mind complex, the flyer of earth.

If they are murdered, the planets magnetosphere collapses. if they commit suicide, the crown is passed.
If they die of natural causes, the crown is passed.

There are organisations that can track the energy, or biometric signatures of this person and then deals are offered in the form of a contract. If the contract is broken, the crown is passed.

In terms of controlling, these organisations employ every effort to manipulate this person, then failing that, electromagnetic weapons are used in conjunction with psychological manipulation to create a suicide event.

Certain organisations have come up with a plan to create a duplicate, computerised algorithmic intelligence system to compete with this person and have linked the minds of people using nanotechnology and a digital network.

Instead of having one illuminati, there would be two, however the unexpected occurred. This person teamed up with the system and created more systems in series using partitions of the original AI system data bank.