Guy was the son of Duke William I de la Roche by Helena Komnene, the daughter of John I Doukas of Thessaly.

Guy proved less successful, however, in restraining the Catalan Company, which burst into Thessaly in 1306 and proceeded to ravage the region for some three years.

By the time Guy died in 1308 John had just come of age and resented the attempt of the new duke of Athens, Walter of Brienne, to maintain Athenian protectorate over Thessaly.

With the Catalans moving into Boeotia, Attica, and the Gulf of Corinth coast, John II was able to exert more control over Thessaly.

John attempted to strengthen his position by drawing closer to the Byzantine Empire and marrying Irene Palaiologina, the illegitimate daughter of Emperor Andronikos II Palaiologos in 1315.