He has a good side (but not that good) and a bad side (but not that bad), each rearing at a different point in his life. No need to pigeon him into a hole.
It's the dad's sister, so the main pair's aunt.
She was kinda shoo'ed out of frame a bit too quickly. But from the brief flashback last chapter, she did seem somewhat distraught.
She definitely didn't seem happy about welcoming the MC.
I'll admit that it's abit of a chekov's gun. But her agreeing that it's a likely conclusion doesn't make it more likely to be true. And this entire chapter was built too much on the hook of incest being a roadblock of their relationship. The author doesn't have any good way to subvert that.
PEAAAAAAAAAAAAAKKKKKKKKKKKKKK
PPEEEEEEEEEEEEEEEEEEEEEEEEEAAAAAAAAAAAAAAAAAAAAAKKKKKKKKKKKKKKKKKKKKKK
FINALLY!!!! A NEW INCEST MANGA!!!!!!! A GOOD INCEST MANGA!!!!!!!!!!!!!!!!