Sentence:  Oh shut up, Wally, Candy was thinking, although she understood why he couldn't stop babbling. He was <WSD>unused</WSD> to an environment he couldn't instantly brighten; he was <WSD>unused</WSD> to a place so despairing that it insisted on silence. He was <WSD>unused</WSD> to absorbing a shock, to simply taking it in. Wally's talk-a-mile style was a good-hearted effort; he believed in improving the world – he had to fix everything, to make everything better. 
Meaning of the word marked with <WSD> tags:  Not accustomed (to), unfamiliar with.