[2][3] At this point, Manuel placed him as tutor and regent over his young son, the despotes Andronikos Palaiologos, who succeeded John VII as governor of Thessalonica.
Eventually, a deal was reached whereby Mustafa would be kept in exile in the Byzantine island of Lemnos and Junayd in Constantinople, in exchange for an annual subsidy of 300,000 aspers.
[1][7] In late 1420/early 1421 and again in May 1421, Leontares was dispatched by Manuel II to Mehmed I in missions of good will, as reports of preparations for an Ottoman attack on Constantinople increased.
The second meeting was a full embassy to the Sultan's residence in Adrianople in May 1421, perhaps connected with a purported amendment in Mehmed's will that would have made Manuel guardian of his two younger sons.
[9] Leontares released Mustafa and Junayd from their exile, and the Ottoman prince was promised imperial support against Murad II if he would surrender the strategically important fortress of Gallipoli.