Personal use of this material is permitted. They see a dire project need and act on it, though no one asked them to.
Royalty believe they provide unique project and product skills for the organization.
They may, but, in my experience, their controlling actions prevent the project and the team from developing products and cohesive processes. When one team member takes on the royalty role, it prevents the rest of the group from learning what she already knows. Royalty delay projects because they interrupt the normal development loop of creating the product, testing it, fixing it, integrating it, and getting feedback. The royalty must stay in their chosen role, because the participants eventually come to believe that the project cannot make any progress without them. His official job responsibilities were to develop and unit-test a specific part of the code base, check in all the code, and build the system on a periodic basis.