Vincent found a Deep Sleep Potion from Dianne's collection of low-level potions and ascended it to a high-grade one…
He then let Belch drink it since Nerissa wanted to imprison him instead of killing him. Well, they can't let him meet the other members of the Creed since Subordination Impulse Potion isn't omnipotent after all. Putting him to sleep is their only option.
With the weird corruption ability, his fellow members of the Creed might find a way to remove the power of the Subordination Impulse without their knowledge. So it is safe to just hide him and send him later to the Eternal Sun Peak.
Of course, before they did that, Vincent asked him to send a message to other squads that they are still waiting for Joran to appear and that they must hurry.
