Ioannes 456 was the addressee of a letter from Theodoros 15 (Theodore the Stoudite), together with Michael 129 and Basilios 125 in early 821, which addresses them as Fathers and as Confessors of Christ; they had survived the persecution under Leo V (Leo 15) and are described by Theodoros 15 as true leaders and monks (τῷ ὄντι καθηγητάς, ὡς ἀληθῶς μοναστάς); they are styled τοῖς ἐμοῖς πατράσι and addressed as ὦ σεβάσμιοι and ἀεισέβαστοι: Theod. Stud., Ep. 58 (addressed τοῖς ἁγίοις μου πατράσι καὶ ὁμολογηταῖς Χριστοῦ, Ἰωάννῃ, Μιχαὴλ καὶ Βασιλείῳ). They were monks, probably hegoumenoi, and confessors.

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