In 1338 Catherine crossed to the Peloponnese to attend to her interests there, bringing Nikephoros with her. At Catherine's instigation the Epirotes rebelled in Arta on behalf of Nikephoros in late 1338: the rebels seized Arta and the Byzantine governor, Theodore Synadenos, and Nikephoros was crossed over into Epirus. However, Andronikos III and John Kantakouzenos swiftly subdued the rebellion and besieged Nikephoros in Thomokastron. Assuring his personal safety, John Kantakouzenos persuaded the garrison to surrender. Nikephoros was duly married to Maria Kantakouzene and was honored with the title of "panhypersebastos". Taken to Constantinople, Nikephoros remained attached to the household of Kantakouzenos during the Byzantine civil war of 1341–1347. When his father-in-law succeeded in asserting himself as Emperor John VI in 1347, Nikephoros was given the higher rank of "despotes". From 1351 he was entrusted with governing Ainos and the cities along the Hellespont.