would Santi and the other demons be jealous if I invited/summoned other demons into our home?
Also in a lot ofq asks the darling always has her phone, why don’t we just call the police??? 💀
[Is the police really going to help you? Since when has it kept a yandere away? Besides, it's the first thing they get rid of. You won't want to use your phone until it's too late to do so, 90% of the time. To which you might say something like "Oh, but I would!" Yeah, you would, because you know these characters already and you know they're insane. Maybe you wouldn't if it was a real encounter.]
Depends on the character and their personality.
They're all yanderes, so to a certain degree, many of them will feel disgruntled and antsy by the presence of other demons, others won't. Of course, the frequency with which you bring these other demons over and how you treat them greatly affects the reaction you're going to get. Some of them are more sociable and will allow you to bring over demon friends regularly (such as Santi), others are more visibly distrustful and upset (such as Mervin).
Whatever negative reaction they may possess is aggravated if said friend of yours is of the same type they are. Because while things may be different in Hell (as well as locations on the surface where demons tend to flock to), on the surface demons tend to generally be territorial of people and locations- Meaning you can't bring a glutton home to Obie and expect him to tolerate that presence for extended periods of time, for example. This is further incensed if there's a disparity in rank between your "lover" and your friend.
Some notable scenarios are:
As sociable as Santi is, he doesn't want you to have many (preferably none) lust demon acquaintances. And if you must spend time with them, do so with him by your side only. These demons may not feed off you, ever, unless they crave death. They're not to spread their scent on you or try to seduce you in any way. They aren't allowed in your home either;
On that same vein, concubi of lower rank like Lacai and Nena will have negative reactions but may resort to distancing you from the perceived threat before engaging violently;
While Ludwig is likely to start brawling with another unknown wrath demon as soon as they set foot in his territory (you/your home), he makes an exception for Rei- Who he's a fan of. They'll still fight possibly, just not with genuine hostility involved;
Obie will not let another glutton eat anything in your home unless they're in good terms or you've specifically invited them over for a meal- During which he'll likely be chewing the cutlery in silent rage.