I havent played the game since its 2nd release or so. SO im curious how much is progressed
Does the MC corrupt all the girls and take them as a harem ?
Does the MC bring/twist out the evilness deep down in the heros girlfriend and she treats him as a wothless pos thats only good enough to be her human chair ? or pet ?.. In early release it implied she was actually evil and self ambitious deep down. Would of been fun to see how he twisted that out to the surface. Watching her turn the hero into a worthless goon would of be thrilling. I mean there was alot of potential here after learning how she was in the first round of events.
Does the MC finally accept the power ffrom the mother of demons ?
A lot of stuff has added since your last playthrough, so answering your questions:
Yes, Cecille unleashes her evilness and Erin turns out to be the main victim. She mainly humiliates him and without Mars she turns out to be even meaner. You can even allow her to feminize him but I have a guess that you don't care for this kind of content, so you can refuse if you don't like femboy content.
Currently Mars has already had sex with almost everyone in the party, the exceptions being Sera (you can only do Anal with her, vaginal is only if you choose her latest route ending) and Erin (that you can also fuck if you choose the femdom route)
It is possible to have sex with a LOT of NPCs from the village too so if you like depraved stuff and destroying families by turning wives into sluts and husbands into cuckolds, you'll probably love the NPCs content.
And yes, Mars accepts Hellele help for most of the things, but he's still cautious with her.