Subgrounded are effected by forces indirectly. They however cannot be effected by them directly.
This means if Asura attempts to read the book of a subgrounded, or freeze them, etc. It won't work. Hence, books being blank.
However if they are part of a time freeze that was not directed to them, or natural progression of time, it of course does.
Same thing as Destruction. They can be destroyed through spell of regular magic, or suffer destruction. However if Destruction uses the power of destruction to destroy them, it will backfire.
Fate cannot fortell them. However prophecies that involve them, indirectly, will fortell them.
Understand yet?