I've been trying to figure out the difference between だろうか and のだろうか through context in my reading, but it's proving harder than I thought. Here's a passage with both. What is the difference, and why are each used in their respective sentences? If I'm assuming it's the explanatory の, then I think のだろうか has more of an inquiry/worried/wondering feeling than just plain だろうか, but I'm not completely sure.
ギルドに入ってきた私を見て、突然何人かの冒険者が立ち上がる。
まるで、何かに怯えるかの様に。
私が紅魔族だからだろうか。
それとも、私にも冒険者としての貫禄がでてきたのだろうか?