The Curses' return was sudden and explosive. Michael had been thinking about his Curses for a while now, but their return was unexpected. At least Michael didn't expect them to return at such a moment. After all, he was still relatively calm even though his blood was boiling. River of Vigor's energizing serum helped him keep cool despite the rage and fury sweeping through him like a broken dam.
But maybe that was exactly what they were hoping for.
The Wolf Curse and the World Serpent released their curse essence – not curse power – into Michael, triggering his Cursed Seals and Serpent Seals. Michael couldn't even do anything before the Seals appeared all over his body. But that was merely the beginning. Their Curse Essences spread through Michael and triggered Curse Fusion as well.