Idiot with Learning Difficulties

Paradise Lost 3 is like Journey 3 in Paradise Lost 1, even fate having nothing to say.

Paradise Lost 2 was a complex horror story that left him suicidal. It took him years to understand. At least it was in a language commonly understandable. Paradise Lost 3 follows the extremes, except it’s in a language known only to him and will never end.

How can a seemingly quiet disability be so destructive – twice?  And in the context of hemi half-eyes?