Potential Comic Spoilers: Answering Lore Questions (Patreon)

First of all thank you ExoticSunMushrooms for the questions! FYI the universe is still in a very early stage and all of these are subject to change. but I'm gonna answer all I can for now :)

What was the deciding factor for the machine heavy realm to invade the demon realm?The empire of machinery is named Bretania, they come from the realm beyond the Demon realm, the realm where they completely sucked the life dry to fuel their machines. And now they’re invading the demon realm for resources. Mainly for hunting cosmic whales as the magical power of their oil powers their city and keeps it floating in the air! *Think Bioshock: Infinite, that's what I was going for :)  And throughout their invasion they have been trying to eradicate local cultures and religion, they destroyed the demon shrines,  hunted down the dormant demons and made sure they never wake up, find and persecute carriers of Varla’s blood so that they can’t awaken the demon etc.  

Is there a magic system, you mentioned, that bloodlines tie into certain demons for pacts.
The Demon Realm is full of wonders and magic. The source of magic comes from mythical creatures across the lands and the Demons. But only the chosen few can make blood covenant with the demon and draw power from them. And those people are carriers of Varla’s blood. TLDR Varla was the first human to make blood covenant with the demons 10,000 years before the event of the comic :)

Are all the main characters from the demonverse connected (like from one village) or are they from different parts of the demon realm and if so does the cultures differentiate to a point, for example, where one clan mistrusts another? Or perhaps there was a generational feud between two regions? Or is it generally more peaceful than other realms?
For now there are a total of 6 nationswithin the Demon realms (though, the actual number of Demons I don’t know yet) :) all are diverse in cultures, languages and ethnicity. All of them have a long history of conflict and alliance with each other. After the death of Varla, her descendants declared war on each other (cuz human being human XD) thus divided the Demon Realm into 6 nations, each with their native Demons. So, yeah. Long history of war. As a result of the war not all regions are prosperous. The regions that lost the war had to seal their Demons away and never to be reawakened. And ofc the victors are more prosperous and the Demons that led them to their victory roam more freely and have better connection with their people. Feud, discrimination, and historical scar will be present for sure. But they will have to put that aside to fight against the empire :)