^ I tend to agree with MagickMike, also spontaneous self-evocations by spirits I wasn’t expecting - I’m going to be lazy and copy-paste what I mentioned before on this, because I think it’s relevant:
my basic theory on why is that what you believe may affect the manifestation, and therefore, how the spirit appears and reacts.
You know how, to get online and view a website, you need a program called a browser?
You can set browsers to make all the text on sites come out a specific way, you can block javascript (which gives a lot of the interactive functionality & other aspects on a web page, and blocking it can totally cripple the way some sites display) - and the belief you take into any magickal interaction seems to be like that.
It seems to affect what kind of manifestation you get, including limiting some of the ways the spirit will act, or what it will say to you.
Note that even with 25+ years experience in magick, I’m still only saying “seems to be” because I wouldn’t presume to know it all.
So, belief isn’t a passive thing, in magick - it can affect what you get delivered to you.
This site has a clear comparison of the different descriptions from grimoires of the very same being: LittleDoomWitch - Buné
Check the link for “Demons” in their menu for more comparisons of the very same beings as seen by different magicians.
I covered some of the reasons a spirit may appear differently in this post: