Asmodeus summoned me while I was carrying my demonic Child and he was exactly as you described Diazin - fierce, intense, very kind of magnetic and impressive, with a strong air of authority.
I talked to him briefly, he was mainly asking me questions and gave me some advice (for any traditionalists who dislike the idea of a human being summoned by a demon, and questioned, my “pregnancy” was something of a game changer and I entered into a different kind of relationship with demonic entities as a result. Not everyone’s cup of tea, but rational within my worldview, practices and so on).
Because I went to him, I saw him in a form similar to a lot of high-level demons, as a cubic chamber with a rear wall that contained sentient moving scuplted glyphs. He didn’t form himself into a human shape, unlike for example Paimon or Amaymon, although I don’t know if that means anything, I never request demons or other entities to take a particular form because I like to see them as they want to present themselves, I find it more intriguing.
Respect would seem to be the keyword here, his impression both commanded it and he showed me respect by the things we discussed - I didn’t get a “trickster” vibe or anything unpleasant from him, and he took care to call me when I wasn’t actively doing anything else, it was more of an invitation with an element of authority than anything else, and someone like me is never going to refuse an opportunity like that.