John VI Kantakouzenos
Shishman did not follow his family and fled to Constantinople. He was immediately sent to the Byzantine regent and later emperor John VI Kantakouzenos, who acknowledged him as Emperor of Bulgaria. That act infuriated Ivan Alexander who demanded that Shishman must be deported to Bulgaria and threatened with war. John VI Kantakouzenos answered that in case of war the Byzantines would transport Shishman to Vidin with ships where the proximity with his family's domains would eventually lead to a civil war.