Asen dynasty
Michael Asen
Son of Tsar Konstantin Tih Asen and Maria Palaiologina Kantakouzene (born c. 1272). Proclaimed co-emperor while still a child. In 1279 he was sent with his mother to Constantinople; in 1300 part of the Tarnovo nobility called for him as tsar against Theodore Svetoslav, but his bid came to nothing.
Biography
Michael was a son of Tsar Konstantin Tih Asen and his third wife Maria Palaiologina Kantakouzene, born around 1272. While still a very small child (hardly more than two years old) he was proclaimed co-emperor — a move that formed part of his mother Maria's efforts to secure the succession and to support her struggle against Emperor Michael VIII Palaiologos.
After his father fell in the uprising of Ivailo, Maria married the rebel himself in order to keep the throne for her son. In 1279, when John III Asen entered Tarnovo, Maria and the young Michael were sent to Constantinople.
Michael's name resurfaced around 1300: part of the Tarnovo nobility, opposed to Tsar Theodore Svetoslav, sent representatives to Byzantium and asked for Michael as tsar. The attempt came to nothing — according to Pachymeres he attacked but achieved nothing and wandered "outside Tarnovo." This is the last notice of him.
Sources
“От този брак Константин Асен имал един син — Михаил.”
— Genealogy and Prosopography of the Asen Dynasty 1186–1460, p. 116