Okay... My brain is on crack... So far, I made a very interesting Creepypasta/Slenderverse headcanon. Mind you, I came up with this on the fly as I was taking a walk, so it may seem a bit odd.
What if Slenderman creates proxies and Zalgo creates Creepypastas so they can take over the world and shape it as they see fit?
It does make some sense. For example, the tugging feeling Jeff got when he got those "feelings"? That could've been Zalgo controlling his mind. However, why do most Creepypastas take Slenderman's side? Slendy stole them from Zalgo's army, which makes my headcanon as to why they are portrayed as enemies.
However, this is just a headcanon, and a sudden one at that. Maybe it's something in my coffee that makes me do this. Or too much time on my hands. Who knows? Until next time, my patients.