It's Pia, since they are both full blooded beast (or what you call of that, lol)
Both..but there is high chance it will be Pia because they are both perfect form and the prince has taken a liking to her... I believe in chapter 3.14 when One is born at his highness chambers the prince servant changes the prince before heading to breakfast and tells him he looks very handsome and pia will fall in love with him more.. so even his servant is aware that the prince favors Pia alot more than nail. At least for now thats how it seems. Even One has a chance since they aren't far apart from age but Pia is head lead
It has never been both, it's always been Pia.
No it's both .. but pia has a higher chance since she is full beast and thus have more magic.. and the prince likes her. The early chapter explain that
No, you're either misremembering or misinterpreting something. Nils was never in the equation. The point of the meeting was because they are both perfect bestials, which is why the king pushed for them to be engaged. See vol 2. chapter 8.
Who is the one engaged to the prince? Pia? Or Nils? I assume it's Pia because he does like to tease her a lot as a kid. But also because she's a beast, and will be the one inheriting the family. Bet them royals love that.