Some papyri aren't bad for this either, e.g. Oxyrhynchus 119:
Theon to his father Theon, greeting. It was a fine thing of you not to take me with you to the city! If you won't take me with you to Alexandria I won't write you a letter or speak to you or say goodbye to you; and if you go to Alexandria I won't take your hand nor ever greet you again. That is what will happen if you won't take me. Mother said to Archelaus, "It quite upsets him to be left behind (?)." It was good of you to send me presents ... on the 12th, the day you sailed. Send me a lyre, I implore you. If you don't, I won't eat, I won't drink; there now![
https://en.m.wikipedia.org/wiki/Papyrus_Oxyrhynchus_119