In this article I seek to show in what manner the Stoic principle of total blending, illustrated by the example of the penetration of fire into iron, finds its refraction in Byzantine Christological teachings. According to the Stoics, total blending occurs when one body accepts certain qualities of the other, while remaining itself, or when both mixed bodies acquire qualities of each other while preserving their natures. I argue that Origen’s use of the example of incandescent iron had an effect on the later theological discourse. There it appears in two contexts, Christology and deification. In this article the focus is on Christology. I claim that the example was introduced into the Christological discourse by Apollinarius of Laodicea. Then, I investigate how it was transformed in later theological writings by (Ps.-) Basil of Caesarea, Theodoret of Cyrus, Cyril of Alexandria, Sever of Antioch, John of Damascus, and the Corpus Leontianum. In this context, I pay special attention to the discrepancy between John of Damascus and Leontius of Jerusalem as regards the issue of the complexity of Christ’s hypostasis. I clarify the causes of this discrepancy.