"I- yes sir, thank you sir."

He stumbles a little as he leaves, but doesn't actually fall over. He can be heard making his way back to his room, where he curls up in the space he made at the head of the bed (it feels safe).

Castiel stands in the living room, monitoring Nova's soul long enough to ensure that he won't try to hurt himself again. 

He doesn't. But that doesn't mean he won't in the future, just that being told not to is still fresh in his mind.

The next few days pass uneventfully, the only change being the subtle improvements in Nova's control over his grace and abilities.

Nova seems to settle somewhat as he realises he is making progress, even if by and large he is still somewhat unsettled by the strange change to his living arrangements, and perplexed by his new guardian. If there are any more incidents of him harming himself, they're cleverly hidden as accidents.

Castiel stayed close, never leaving for more than a few hours at a time to buy food or other resources for Nova. About a week later, Castiel receives a summons to heaven to give a report on the Nephilim's progress.

He isn't doing badly. His control is improving, and while he's still timid and unsure, he seems a little less convinced that Castiel is going to hurt him for making a mistake.