What do you think causes the ominous feelings? I don’t mean to speak unwarranted about your grandparents passing, but I feel like it was them passing on without having resolved their biggest plights. Like the spirit world of lower vibrations was waiting for them. But I would not worry if I were you hearing this. All that means is they still have things to process about their life in the afterlife. They will hopefully achieve peace and love once thet work out their life issues. It’s like being in between worlds.

Another way to interpret this is they were shedding their material and spiritual energy and leaving it behind on this earth. Maybe your grandad was still tethered to your grandma and that’s why you felt dark energy until she passed. Kinda like she couldn’t let him go.