Well, for one, I decided to change it from the 18th century to the 19th. So, to help you guys get a whole idea of the 19th century here are some pictures that are related to the story. Hopefully, it'll help you guys out. 

Okay, to start it off, the 19th Century was during the years, 1801-1900. There is no more slavery as well, since it was banned. There were sports like football, rugby, cricket and baseball.

That is a hibiscus flower, a purple one at that. (Like the one in the first chapter).

This is a rough idea of what Suho's manor looks like. Though, it's much more fixed up.

Dresses, that's what the women wore. These puffy dresses, they would also wear tight corsets. This is what Hibiscus is to wear.

Basically, the men wore lots of suits, well the more fortunate ones. (Like Suho for example) And the less fortunate wore clothes like the guy on the left in the RIGHT picture. That's what D.O would likely wear, but a little different than that?

If you guys have any questions, just post a comment here. Don't be afraid to ask.Thanks! :)