According to the hagiographies, Joannicius spent the rest of his life as an ascetic on Uludağ, with years dedicated to solitude, study, and prayer. Joannicius spent most of his time reciting the psalms and meditating on the life of Jesus, but the hagiographies also ascribe some miracles and prophecies to him. Among the many stories related in the hagiographical sources, Joannicius is attributed with saving the island of Thasos from snakes, leading Greek captives out of prison, and saving a nun from breaking her vow. In one of the more famous stories, Joannicius found a nun near Uludağ running away from her cloister, intending to marry. Joannicius intervened, allegedly taking on all the pains of her sin and allowing her to remain a devout nun. Joannicius was allegedly so close to God and so devoted to solitude, he was capable of making himself invisible.