Famous for her beauty, Sultan Mehmed II, who had conquered Constantinople in 1453, took her into his harem after his conquest of the Morea in 1460, but soon decided to leave her in province, possibly due to fear of being poisoned by her.
Instead of remaining in the sultan's harem, Helena received a pension and large estate at Adrianople, where she lived until her death of unknown causes around 1469, only about 27 years old.
[8] After Sultan Mehmed II, who had conquered Constantinople in 1453 and now ruled as the suzerain of Demetrios and his co-despot and younger brother Thomas, invaded the Morea in 1458 because he had not received the agreed upon tribute by the two despots, these marriage plans fell through.
From 1459 to 1460, Demetrios and Thomas fought a civil war over control of the Morea, which ended only with the intervention of Mehmed II and the annexation of both their territories into the Ottoman Empire.
[1]The reason for Helena didn't remain in the sultan's harem is unknown, but it is possible that Mehmed II feared that the girl might attempt to poison him.