to foreshadow the the ending and make it believable.
Decompression sickness manifests ITSELF with joint pain and it can be fatal.
'Itself is a word that is usually used as the object of a verb or preposition to refer to to an inanimate thing or an animal which has been mentioned previously as the subject of the sentence.
Google will help you a lot if you research
It is d. when a character, place, thing, or event in a literacy work stands for a larger idea
