Now where to begin on one?

Well basically snakes in fiction that have been betrayed as cunning and deceitful even if they do have part in some myths just that they are a double-edged sword and I know I may already I said this but I think the hypothetical snake Palsmen Luz could make may give some negative influence into her ear.

What kind of bad influence and what kind of snake is anyone's guess at this point.

It could be a Cobra a python Anaconda any of those and others even if it's meant to protect Luz will have a hidden agenda and what if it can take the from of a human?

Heed my warning they will always be a snake in the grass.