Yoel of Londor is at Firelink Shrine now, and offering me free levels. Some basic research indicates to me that if I accept them, I'll get a Dark Sigil, which causes me to Hollow on death. And possibly other things.
I've also seen some ways I can rid myself of the Dark Sigil.
I'm curious what the pros/cons are to going down this path. Are they basically free levels if you get the Dark Sigil, level up, and then cure yourself after maxxing out the free levels? Is there an upside to keeping it, or being Hollowed? What are the downsides to be Hollowed?