No. The demons are not naturally wicked because everything which exists, so far as it exists and has a particular nature, tends naturally towards some good, since it comes from a good principle.
Now it is manifest that every intellectual nature is inclined towards good in general, which it can apprehend and which is the object of the will.
Hence, since the demons are intellectual substances, they can in no wise have a natural inclination towards any evil whatsoever; consequently they cannot be naturally evil.