John III Doukas Vatatzes
In an effort to counterbalance Nicaea and strengthen his position, Leo concluded treaties with the Republic of Venice in 1234 and 1236, but his brother John Gabalas, who succeeded him when Leo died in , was clearly in a less powerful position, and he soon recognized the overlordship of the Nicaean emperor John III Doukas Vatatzes. In exchange he received the high titles of "sebastos" and "megas doux", and likely the hand of an imperial relative (possibly one of Vatatzes' sisters).