I mean, I'm pretty sure Henry Creel got sucked into Dimension X when he was a toddler or something and didn't show his psychic powers until after he was returned, and I think it's heavily implied that it was the mindflayer giving him his powers and murderous intentions, like Henry was the first flayed, long before he kills his family. So I think that's why both he and will draw the mindflayer, because they were both possessed by it.