The situation: My dance teacher, the son of my Shansi mentor, and myself are chatting, though I am largely in a passive role.
Our levels of social importance:
My dance teacher: The most important. She is safe using the lowest level of Javanese with the son of my Shansi mentor and myself.
The son of my Shansi mentor: In my head could quite possibly be her peer. Though she is—I believe—older than him, she is not considerably older.
Despite the age difference between him and myself, we are quite informal. I do not hesitate to use aku/kamu with him and would probably also use informal Javanese with him, except that he would just laugh at me because my accent is so bad.
Me: Obviously the least important. I am younger and in the role of a student. I use saya with my dance teacher.
The observation: The son of my Shansi mentor spoke with a good deal of mixing between Indonesian and Javanese. Not unusual. However, when he used Indonesian, he referred to himself as saya. When he used Javanese, he referred to himself as aku.
My commentary: This saya/aku contrast struck me as odd. He was using saya to show a level of respect and formality towards my dance teacher. However, when speaking Javanese he was not, as far as I could tell, speaking up to her in any way. I have been told that aku feels very informal in Indonesian because it is very informal in Javanese. If this is the case, why wasn’t he using the more formal Javanese kula?
The conclusion: I still have a lot to learn about levels of formality in real life.