Who is the Master?

I find it curious that in the chapter 39 of sefer Breishit (book of Genesis) the name of Potiphar is mentioned only once in the first verse, only in the context of the act of slave trade:

39:1 Now Joseph had been brought down to Egypt, and Potiphar, Pharaoh's chamberlain, chief of the slaughterers, an Egyptian man, purchased him from the Ishmaelites who had brought him down there.

The next verse refers to ‘his Egyptian master’, and then, every verse after that, throughout the chapter, we only see the word ‘master’, but never the name.   Even Potiphar’s wife is only mentioned as  אֵשֶׁת אֲדֹנָיו , wife of his master, rather than wife of Potiphar, his master. 

I noticed that omission at the end of the chapter in verse 39:2: So Joseph's master took him and put him into prison, the place where the king's prisoners were imprisoned, and he was there in the prison. Here not only the name of Potiphar is missing, but even the Pharaoh is also not mentioned explicitly, only as a king.

The Egyptian man is used as an agent to start the story, which subsequently develops on different levels. Who is the true Master of Joseph, and who is the King?  Who the wife of the Master, love sick with Joseph – is this truly the corrupt, obnoxious Egyptian woman, or the divine Shechina, trapped in the body of the kidnapped woman, too ignorant to know how to handle her feelings? 

The house of prison, בֵּית הַסֹּהַר, is described in the Midrash as an underground dungeon with a very narrow crack of a window, shaped like a crescent.  So is the beauty of Joseph, his mind, his personality – a narrow crescent of a window that allows a glimpse into an overwhelming beauty of olam haba, the world to come, the world above, the hidden beautiful world, once expressed in the design of the sanctuary of turquoise, gold, purple, scarlet red and linen white, the world of peace, filled with the light of Shabbos.