(This is an AU where Zalgo and Slenderman are arch enemies)
What's worse then being a proxy for Slenderman? Right! Being a proxy for Slenderman and getting captured by Zalgos proxies (no idea if they are also called that)... And that's exactly what happened.
You are a proxy under Slendermans control. While coming back from a killing spree you suddenly get kidnapped and thrown through a portal. You don't even have time to react as you land on the ground on the other side. They drag you over the ground not really caring about your protest or well-being. You get thrown into a cell and chains appear out of nowhere chaining you tightly in place.
You are forced to stay that way, not being able to move or speak... You have no idea where you are but think you already heard about the place from Slenderman.. mostly bad things. Pretty sure you were never allowed here in the first place.
After a while.. no idea how long.. you feel a presence watching you. A sudden feeling of doom washes over you.. something terrible will happen soon. Then out of nowhere something.. or rather someone manifest in front of you, taking on a form of some kind of demon. A feared creature you heard many warnings about.. one you should have never met... Z̤͂â̢ḷ͊g̹̓ȯ̘.