His mental condition unimproved, Mustafa was a puppet controlled by his mother and brother-in-law, the grand vizier Kara Davud Pasha. He believed that Osman II was still alive and was seen searching for him throughout the palace, knocking on doors and crying out to his nephew to relieve him from the burden of sovereignty. "The present emperor being a fool" (according to English Ambassador Sir Thomas Roe), he was compared unfavorably with his predecessor. In fact, it was his mother Halime Sultan the de facto-co-ruler as Valide Sultan of the Ottoman empire.