Achilles had learned his manners from the years of growing up as an adolescent with Lycomedes' daughters. There was an expectancy for manners, for men and women. He took the tea with a thankful nod of his head. He didn't intervene yet, but it was obvious as he watched the women talk that he had something to say.
As his mother continued to bash his father in a way he would like to physically he sat the cup down on the saucer with a loud clank. He held his hand up in apology. "I can speak for myself Mother." He wasn't trying to be too brash with her, but she was riled in a way only he could compare to. This was going to sour his mood and he really had just found that sense of personal belonging.