hmm

Apparently they are not blood related so its not rlly incest. But I get they grew up and lived together as siblings

they aint siblings by blood coz girl is adopted but like, how can one see someone in a romantic light when they were introduced to each as 'siblings' from a young age • ‿ ,•

But there's a tendency to feel attracted to her knowing they are not blood related. From my OPINION, Eugene doesnt actually see her as siblings because from the part where he stole her candy they blushed (they were not still not siblings at that time) and since that moment he started changing how he treats her. Thats why he came back for her when he tried to leave her. Bottom line, he mistaken his attraction to her as a sibling love. ╮(￣▽￣)╭ idk i just wanna make it romantic tho

then ig that would 'justify' eugene's feelings. thank you ♀ that made me feel a bit better

But honestly how does she look so similar to the biological sister

Right?!

Can't say for Hari, but out of all brothers Eugene was the only one who spent the less time with Hari due to his circumstances(being the heir to the duke title). When they were young, they basically only spent like... A year(?), or less than two years to properly developed siblings relationship under their parents guidance, especially since they were hostile in the beginning.

Also he was brought up more strict than his brothers due to him being the heir, and basically only did what the parents asked him to; caring for his siblings. I can see why he didn't really consider Hari as his sister(like his sister that died), but still considers her as part of the family.