Weakness

Based on Hollow Ichigo's quote:
(To Ichigo) "'I'm going to keep getting closer and closer to you. And not just day after day, oh no. It's going to happen much faster than that! See I'm already closer to you than I was a moment ago. And I'll keep getting closer and closer to you, until I swallow you up and then, you'll disappear. Things are not turning out well for you at all, are they? (laughs) See you around"

I've always liked to imagine Shadow/Dark Link being kinda like Holllow Ichigo, waiting to take over and kill everyone and destroy everything Link cares about...