How do Ты write a letter to Peter

There is no specific way. Ты just write to him. Start slow though and don't rush him with things about yourself. And be patient, he will be very hesitant, and doesn't usually write back. He will leave Ты signs he was there to read it though. Make sure to imagine him opening and Чтение the letter, it's a universal thing that will send thought waves to him and tell him to come :)

Anything Ты want really!You can talk about yourself или ask him questions.Make it interesting!

Ты could maybe tell him that Ты believe in him and Ты can ask him to visit или say you'll always sing and tell him stories, just some suggestions as they сказал(-а) anything Ты wanna write really :))