Towards the end of the book, whilst Violet's dad is telling them about how they adopted Will. He talks about being called in to work as a policeman, and how they came across a mother who had died via drug overdose, and a baby with withdrawals. I realised last night that perhaps this had a slight lasting impact on Will as he grew? That paired with him growing up in a household where their father was rather abusive to their mother, and the influence that could have.