Ka kammala wannan jumla: A shekara ta 1394, sarkin Ottoman Bayezid na ɗaya ya kai wa Constantinople hari. Manuel ya bar garin a cikin 1399 don yin balaguro a Yammacin Turai don neman taimakon soja, kuma ya amince da John VII da yin aiki a matsayin mai mulki a Constantinople, yana lura da tsaronta. Duk da zargin da ake yi na yin makirci tare da Ottomans, John VII ya riƙe birnin cikin aminci a duk tsawon tafiyar Manuel na tsawon shekaru uku da rabi, yana ƙin miƙa shi ga Bayezid. Barazana ga Constantinople ta ƙare tare da shan kashi na Bayezid a kan Timurids a
Yaƙin Ankara a shekara ta 1402. Bayan wannan yaƙin, John VII ya yi shawarwari mai kyau tare da ɗayan 'ya'yan Bayezid, Süleyman Çelebi, wanda ya tabbatar da cewa babban birnin Thessalonica, wanda aka rasa ga Ottomans a 1387 saboda ayyukan Manuel, ya koma ikon mulkin mallaka. Duk da amincin John VII, Manuel ya kore shi cikin kunya da zarar ya dawo a 1403, kuma su biyun sun sake zama abokan gaba. Wannan rikici ya kasance na ɗan gajeren lokaci, kamar yadda aka sasanta su 'yan watanni bayan haka kuma aka yi sabon yarjejeniya, wanda aka ba John VII damar mallakar Tasalonika kuma an yarda da shi tare da cikakken taken na sarki. Daga shekara ta 1403 har mutuwarsa a shekara ta 1408, John VII ya yi sarauta a Tasalonika a matsayin "Sarkin Dukan Tasalonika", tare da fadarsa ta musamman. Tassalunikawa sun ɗauke shi mai sarauta mai kyau, kuma aikinsa a al'amuran coci na yankin da kuma gyara ganuwar birnin ya sa an tuna da shi sosai.