And then he can begin inquiring into their true names. It seems just crazy enough to be true and if it is true, does one lead them or are they more of a cohesive unit? Let's say they do have a leader and there is one Joker that reigns supreme.
Many comics have said that Sans is the older brother... But I haven't gotten any proof yet. It makes sense that Sans could be the older brother... But it makes just as much sense that Papyrus could be the older brother.
Papyrus is perfectly fine with manipulating or torturing others to get what he wants. The only people he shows any sort of bond with is his brother, Sans and the head of the Royal Guard, Undyne. But Sans isn't safe from Papyrus' wrath, as their relationship revolves around their hate towards each other.