Not only the same page but also "in the same team" or "on the same side of a conflict". That does not necessitate that they think exactly the same thing.
It could also be literally on the same side of a river.
Det är intressant.
So "Come to the opposite side" becomes "Kom till motsatt sida". But something like "Come to the dark side" becomes "Kom till den mörka sidan". Is there a sort of list of adjectives that only precede an indefinite such as samma and motsatt? Much appreciated.