Peter shows some signs of embracing cole's island practices. What are these?

The morning after Peter's parents leave the island, Peter and Garvey accompany Cole to the freezing pond, although only Cole gets in, and then they carry the ancestor rock up the hill again as well. Days go by without any change in Peter, but eventually he (Peter) rolls the ancestor rock down the hill and attempts to enter the freezing pond. At the end of the chapter, Peter invites Cole to sleep inside of the warm shelter instead of the cold tent.