Iwan Asen I, Tsar of Bulgaria: NH genealogy

From Wikipedia (accessed 13 Dec 2021):

Eudoxia was the fourth daughter of the Nicaean emperor Theodore II Laskaris and of Elena Asenina of Bulgaria. Eudoxia grew up as a princess at the court of Nicaea, where Constance II of Hohenstaufen, widow of her grandfather John III Doukas Vatatzes, also lived. As a young girl, Eudoxia was promised to the royal family of Aragon as a bride for their son, the future king Peter III of Aragon. After the Palaiologan usurpation of the imperial throne, both ladies (dowager empress Constance and Eudokia) fled, travelling the same route from Constantinople to Tende and Sicily, respectively, and, years later, both sought protection at the kingdom of Aragon under king James I.

Soon after the re-conquest of Constantinople in 1261, Michael VIII Palaiologos, until then regent and co-emperor for the infant John IV Laskaris, had himself declared sole emperor, solidifying his position by having John IV blinded and imprisoned. John's three sisters, Eudoxia among them, were hurriedly married off to foreigners, so their descendants could not claim to the imperial succession.

The young Eudoxia was married in Constantinople on 28 July 1261 to Count Guglielmo Pietro I of Ventimiglia and Tenda (1230–1283), count of Ventimiglia and Tende, a Ligurian region then at the service of Genoa, allies with Michael VIII. This marriage originated the house Lascaris de Vintimille, which stood until the 19th century as a powerful French family. [...]

Before reaching 30, Eudoxia fled from Liguria to Aragon with her daughters Beatrice and Vatatza. Some say it was at the time of her husband's death or on being refused by him. Living at Xàtiva and Zaragoza and Castella, she travelled on diplomatic missions for King James II of Aragon.

Eudokia married Guillaume Pierre I de Lascaris de Vintimille about 1263. [Group Sheet] [Family Chart]

Children:

5. Jean I Lascaris died before 1344.