Does this manga pertains facts happened in history or fiction made by the mangaka?
If I remember correctly, Hephaestion in the recent chapters is a Macedonian general not a separate personality of Alexander.

Well, I was veeery bad at history at school But I think the author is using some people that really existed and historic events, but at the same time adds things from himself. For example, Alexander is a real person, but this split personality thing and his character in general is made up by the author.
I think it's the same with Vinland Saga - characters such as Canute or Thorkell are real, but their personalities, looks etc. are the author's invention.
I hope it's understandable

I think Iwaaki skipped out on making Haphaestion an actual person to avoid the homosexuality subject. Plus, as the above guy said, he's taking creative liberties on expanding and whatnot some character's personalities. Other than that though do you even know what pertain means?

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hey bro