Blame It On The Rain

It happens, sometimes. These days, more often- but back, back when it first started, it'd been a rare occasion.

Norman will disappear. Or he'll suddenly freeze up and walk away for no reason. Or he'll start screaming about revenge and the afterlife and seeking vengeance on those who've wronged him, his normally gray-blue eyes glowing a bright, highlighter green color.

(Norman goes missing, and Dipper has a good idea as to where he might be. It'd be pretty romantic, standing in the rain in the forest glade where they first met- But the dead lady possessing Norman is kind of putting a damper on the mood.)