Xenon

I also think it likely that it's due to the "closeness" of a Surge to a Shard. I think it may also be a matter of using the proper light in conjunction with that surge. Kaladin uses stormlight (Honor's Light) to power Honor's most pure surge. Lift uses lifelight (Cultivation's Light) to power Cultivation's most pure surge. I'm curious if another Edgedancer would have been able to make Regrowth work using stormlight while under suppression, if they had been awake. Edit: That is, if Progression truly is the most pure "Cultivation" surge, as Adhesion seems to be for Honor.

I don't remember anything more specific than that, though I only did a quick read for the first time. I suspect that they were just the assistant, though now I'm wondering if they were taken away like was suggested, were they ever picked back up? Assuming the poor fool was just a normal person?