Grandpa also tried to help, however, something happened that he didn't expect. Have you ever wondered how apathic powers work?
Apathy were considered to be vampires of Investiture, which flows through the body due to the combination of mind and soul, being as such a numbering in layman's terms.
Of course there was a way to generate negative energy, which could make someone imperceptible by canceling the threat level to 0, they had experienced it against the Destroyer.
The apathy can take those numbers and use them to strengthen themselves, the most powerful one was capable of ripping out the source of life from beings in one fell swoop and used as fuel to mutate itself in hyper-evolution rates, it was named in different ways, Fendahl, The Darkness, The Soul- Destroyer, however, the important point is that the Apathy are only parasites on the physical plane that absorb astral energy from the mortal body, so how powerful should the equivalent of them be in the astral Realm, the reflection of reality, Or rather, reality is the reflection of the Astral realm?
The first to fall to the ground was Grandpa, he didn't move, it's not like he could after he died, while Xor and Jack felt as if something fought fire with a higher fire, tearing out parts of their souls.