The edge of paranoia always apparent in Colin's dealings with the world was becoming more pronounced; and meanwhile, Tessa was pretending to be oblivious, doing absolutely nothing to help alleviate the dreadful, crushing strain. (The Casual Vacancy, by J. K. Rowling)
Does the negative sense in ‘nothing’ permeate all the rest words that follow? Or does the following to-infinitve is an independent meaning unit that is blocked away from the negative?
If the former is right, I guess you might say to-infinitive modifies nothing; if the latter, you might say to-infinitive is an adjunct denoting a purpose.