[1][2] In 1275, the Byzantine Emperor Michael VIII Palaiologos sent a large army to subdue her recalcitrant father.
John I gave the necessary aid to the sebastokrator, in exchange for the marriage of Helena to his brother, William I de la Roche, the future Duke of Athens (r. 1280–1287).
[4] Following William's death, Helena served as regent for her underage son until his coming of age.
[5] In 1289, she refused to recognize the suzerainty of the new Prince of Achaea, Florent of Hainaut, and the Angevin King of Naples, Charles II, as the common liege-lord of all Frankish states in Greece, had to force her to submit.
This allowed Helena once again to challenge Achaen suzerainty, and insist on her right to do homage directly to the King of Naples.