[1][2][3] She was the sister of Michael Asen III (called Michael Shishman) and Belaur,[1][4][5] children of the despotes Shishman of Vidin by an unnamed daughter of sebastokrator Peter and his wife, herself a daughter of Ivan Asen II, variously identified as either Anna/Theodora or Maria.
[8] Since the 1250s, the area of Vidin had been effectively autonomous under loose Bulgarian overlordship, and was governed successively by Yakov Svetoslav (died 1276), Shishman (died between 1308 and 1313), and then the future Bulgarian emperor Michael Asen III, all of them receiving the highest court title of despotes.
[13][1][14][15] In that year, Pope Benedict XII (1334–1342) addressed a letter to his "beloved daughter in Christ, the noblewoman Petrissa, ducissae Carnonen(si)," and sought her assistance in bringing her son, the Bulgarian emperor Ivan Alexander, into the Catholic fold.
[16] The Latin term ducissa, "duchess," reflects the Byzantine and Bulgarian title of despoina, which Keratsa Petritsa would have borne as wife of the despotes Sratsimir.
[20] At some point before her death, Keratsa Petritsa converted from Roman Catholicism back to Eastern Orthodoxy, and retired to a convent under the monastic name Theophana.