He was 'insistent' about paying for dinner. [=he insisted on paying for dinner; he insisted that he should pay for dinner]
My friends were 'insistent' that I go. = They were 'insistent' on my going. [=they insisted that I go]
We listened to the 'insistent' crashing of waves on the beach.
(..) Oh. So, you read your fan mail now? I wouldn't exactly call him a fan. He detested me. But he was quite insistent I attend his funeral... and tell you what became of Anna and her mother... so here I am. And that's your answer, (..)2014 The Fault in Our Stars