When we last left Will, he was puking up a slug-like creature that was seemingly leftover from his time battling the Demogorgon , an inter-dimensional monster who claimed the life of Barb (Shannon Purser), in the Upside Down. We don't yet know what Will expelling things from an alternate dimension really means, but we do know that it's not good. Could Will be more tainted from his experience than we thought?