Definitely that carapace demon

they don't move or do anything how can he study or understand them 

All mundanes, i believe, are  potential vessels to become a carrier of the nightmare spell, thats already been said.

Regarding that whether they can ascend multiple ranks in one go be they dormant, awakened, acended, bla bla. Actually yea.

Considering the nightmare spell makes it easier to do that, then why not it be for a mundane, nephis did the same, and well sure she was already a sleeper

But im more or less confident a mundane can do the same, granted they lucky asf

A baby tho, we know saints have the ability to ensure they get a seed of nightmare

So my guess is if a baby is born within a nightmare from an awakened person or even a mundane, they immidietly get a seed of nightmare that is of thr third rank

So, in conclusion, ultra super mega nepobaby

Might be wrong tho

This really reminds me of Sunny in the old days

Sunny taught her well