It's a fantasy role-playing game.

DM: You are Pike Trickfoot, a gnome cleric . You are the member of the famous group of adventurers. Previously, There was a cart of horses pulling a group of four gnomes that all eventually revealed themselves to be family of you Trickfoot.  After taking them in, whether or not  Vox Machina was  excited or eager to, nevertheless  they  treated them with hospitality, gave them a place to stay, gave them food for the evening, conversations were had,  and  information was passed around.
DM: "I find little in faith. However, the exorcism is based in divine magics and some bits of information I've gleaned from the Age of Arcanum, long ago, back when possession was a common thing and gods still walked the earth. What I've found--" And he leans forward on his stick. "-- is to perform this. Pardon me, it's the breakfast. All the oatmeal. It's good for the fiber."
Player: It sure is.
DM: "What I would require would be the highest point on the highest mountain in the vicinity. As high up as we can go. Like somewhere in those mountains there." He points a broad stroke to the north, northeast, to the Alabaster Sierras that surround the Parchwood. "And when the moon is full, as that was when the original curse was cast upon us, there, we hallow the ground to prepare. Perhaps you or another individual of a clerical background could do so, and it does take some time to hallow it. But with the ground hallowed, and the moon is full, I can perform the exorcism. Now, should the shades be strong enough to survive the exorcism, as they have once before, it will be up to you and your friends to slay them while they're bound on that land. And if you cast them to the shadows where they came, the blood curse on you would be no more."
Player: But they'll come back again?
DM: "They are passed on through the bloodline."
Player: Is there any way to get rid of them forever?
DM: "From an individual, yes. Overall, I know not. That involves silly, crazy god stuff, and, well, they haven't been around often. There are a few things we need to prepare for the exorcism that I don't have the access of. If you wish to go through with this, let me know. If you find this all mumbo jumbo and you don't believe me, I don't blame you, either, and we can be on our way. Choice is yours."
