Theodosius Branas, also called Theodore Branas or Theodore Vranas. Theodosius was called "Vema" by the historian Geoffroi de Villehardouin.

Theodosius was born in Adrianople, a Byzantine subject of Greek origin. In 1204 he married Agnes, Princess of France, the daughter of King Louis VII and the full-sister of Philippe Auguste. Agnes was twice the Empress of the Byzantine Empire, married first to Emperor Alexius II Comnenus, and then to Emperor Andronicus I.

Theodosius and Agnes were of invaluable assistance to the Crusaders ("Latins") of the Fourth Crusade after they took Constantinople and founded the Latin Empire in 1204. Theodosius was one of the first Greeks to support the Latins and acted as an ambassador to Henry of Flanders when the Greeks of Adrianople and Demotica wished to break their alliance from Tsar Kaloyan of Bulgaria and seek the protection of their cities by the Latins.

Theodosius was Lord of Arpos (which the Latins called Naples of Napoli) and Adrianople.