I’m not sure the shadow was there that long. Didn’t Wendy say it arrived around the time Bae did? We saw 6 months later from the vortex to when he meets Wendy and when they’re found out Wendy says he’s been there for “weeks” (way to be vague) but it may not have been quite as big of a time span at least (though it’s still a lot).
In the official podcast they mentioned something about it seeming to follow him? Can somebody back me up on that? There was something about dark magic following him or something and it related to the shadow conversation and the fact that according to Wendy it arrived around the same time he did. I need to stop multitasking lol.