19th End Century Memorandum

Ah.. i was wrong then  sorry for wrong spoiler
Cuz I vaguely remember she's still unsure whether he's her bro or not. And then there's something that made her 100% sure that he's not her bro later after she had slept with him. Which is when she confronted him and told him blatantly that she knew he's not her real bro, this happened after she asked the head maid about the truth, I think?

Anyway I'm sorry for wrong spoiler before. It's been too long since I read it  

Elliot and Liliana end up together and have 4 kids. 

Let me give you the answer since I remember this part. She knew he's not her biological brother much later after they had sex together
Right after they've done it, in the morning MC told ML to start anew with their relationship and forget everything about ML's dark past. At this time MC still thought that ML had done some criminal acts for locking the woman beside her bedroom (which was non-existent to begin with) but ML said how could he forget all of his past (ML was referring to the guilt he had over William's suicide). Then ML cut her out by saying they should keep being siblings and left the room. Then ML met his friend and told him about MC. ML said he hated her because how could she loved him as a man when she's already known that he's supposed to be her brother. He hated her but also loved her at the same time. ML also felt like this towards William. How could Will love him (the love between a couple) when he had been ML's brother for so long. 

He thought that it's in the blood of both the siblings to fall into sin. So in his mind, he was testing Lillian that just like her brother, who fell for him even after they both grew up with each other as brothers, she too will fall for him without caring if he is her (real) brother or not.
Although it wasn't really testing, he was outright seducing her.

I've many things to say but Elliot is basically a hypocrite. Because of his guilt and his anger towards a dead man, he hurt someone innocent and became more and more of a sinner with each wrong step taken. 

Yeah, the back and forth between the main leads is so messy that it would be natural for them to cut ties and move on . I guess Spoilertime apart and finally being honest while also being supportive allowed them to try again and get their happily ever after (honestly Elliott was the one who really needed to be better cause he made some terrible choices). I think them deciding to move past their pasts and not be tied down and Lilian facing her mental problems was what the story was working towards. At least that’s my take. 

So Lilian is not his real child?
Also, I wonder why Elliot's father is so attached to William's father. He even died of grief due to William's death. I have the feeling he never liked Helena.
Btw, what is the meaning of Bluebeard story at the start of this manhwa? 

Oh shit... Was Helena raped? I thought it was an affair and her research was stolen from her. Then I might have misunderstood MTL of the Raws...

That really recontextualizes the whole situation. But the husband does mention wanting to trust her etc so it gave me the impression it was consensual. Do you remember where this exchange takes place that shows it was rape? 

The story makes pretty clear that Lilian is not Arnold’s real child. That Helena has an affair with the man she meets while Arnold is away. There are many instances throughout the story that detail this. I think the fact that their first child looks like William can be chalked up to the Author‘s taking liberties with the story. And of course William and Lilian share genes, they share the same mother, so Lilian can have a child that looks like her brother.

i have a friend who looks exactly like his uncle on his father's side - like looking at a clone. The uncle died when my friend’s mother was only three years old so no need to be suspicious of an affair like Helena lol .