system
Given the following post, respond as if you're commenting on Reddit:
human
[Marvel] Why is Mephisto present in the abstracts meetings ?

He is a skyfather level demon and thus very powerful, but why is he present in the meeting of abstracts ?

He is not a cosmic entity,and is ruler of his own hell,so why is he there ?

Or any of the skyfathers or hell lords for that matter ?
gpt
I suppose the simplest answer would be "Because he wanted to, and nobody bothered to banish him out". 

While he isn't an abstract entity, he is, as you've said the most powerful archdevil in the Lower Realms, so he's powerful enough to make anyone's business his business. 

I would assume other Skyfather gods are more preoccupied with their own pantheons, especially considering that in Chaos War there was a whole slew of godslaying going on, and thanks to Thor, Asgard pretty much pushed aside most of the other pantheons in the mind of the mortals. Even though Russian Winter Guard managed to get their hands on Perun and Chernobog of slavic pantheon, Perun is clearly not as strong as Thor, and Chernobog is basically uncontrollable and does whatever it pleases -\_\_-" 

And Japanese pantheon is probably still ashamed that one of their own started the Chaos War in the first place...