Endogenous Demons usually look something like this. ( again, it will depend on the Ys you use.)

Or if you are lucky enough, some may look like this.

Or even this, if you have enough knowledge and wisdom, or if you have spent a lot of time listening to good old Black Sabbath.

But be warned my Fellow Demon Summoners, as this type could be very deceitful. Don't fall for their siren songs or lullabies.

Now this would be the amazing moment : watch closely how they get busy with eachother, Exos with Endos. at this point they begin to interact. Watch their relations.

now...

If they made too much noise or they get out of control, you have two ways to deal with them.

One way is to simply fuck around with their Psych using this spell:

( pay attention my fellow Demon Summoners, this spell works only when it is m X m )

and there is a second way to control them, which is also more challenging:

By casting either of these 2 spells, you can really fuck them up, preventing them to fool around too much, but be warned,as these ones are a bit tricky. they may not work in your first attempt, so be prepared for the situation.

If at any step, you felt chaotic in your guts about the Exogenous Demons, just keep your cool and refer to this:

Be prepared my Fellow demon summoner : last semester when we came to this point, some of the students LITERALLY ran out of the classroom in panic, straight to the head of the department, Screaming " The Professor is Summoning Demons in here!!! 😱😱😱 "

While your brother kept his cools and respectfully said : please go on Professor 🤓 nothing may stop you in this dark path we crave.. 👹👹

[ disclaimer : the information presented above are only for educational purposes. the author takes no responsibility about the consequences or the results of fooling around with this kind of Demons. also, the information presented above are technically wrong, out of context and non-useful. ]
You get the Idea, Fellow Demon Summoners!