Recently I have read the last chapter of the book Peak. Peak had gone back to New York and wanted to be at the twin's party. When he got there the twins, his mom and Rolf came to greet him. Peak's mom and Peak had a talk in the kitchen, then Holly came in and talked to Peak for a bit.
I think Peak was actually happy to see Holly, though she had been a pain on the mountain. He was obviously happy to see the twins, mom and Rolf too. Here's a quote, "The two Peas dropped their presents and threw their little arms around my thighs. Mom was next, then Rolf." I think this quote shows that his family missed him a lot. I also suggest you read Joey's blog. I think he did a great job explaining the twins.