[Someone]

It’s confusing because you have to know the nationality of a person to know how to capitalize their surname (In Flemish Dutch, prepositions that do not start a sentence are uppercase if they’re part of a name)

And nitpick: you likely meant “Willy Vandersteen” (https://en.wikipedia.org/wiki/Willy_Vandersteen), but that would be a bad example as it, I think, would always be capitalized, also if he were Dutch.