Name (simile)
When the narrator asked the alien his name he answered John, which is not a name for an alien so Sally laughed. He was not offended by her laugh and said that he had a name in his own language and made some noise with his mouth. Sally could not repeat it as it did not sound like a word to her, but still “it was a beautiful sound – like a birdcall, only sadder”. The language of the alien is compared to the singing of birds.
Charlie the snake (metaphor)
Charlie is presented as a cruel and hostile person, metaphorically he is even shown as a snake, when says Sally to get him out of the café, his manner of speaking resembles hissing of a snake. Along with hissing Charlie is scowling and nodding, which adds negatively to his appearance. The final stroke accomplishing his image of a snake is his slinking manner with which he gets back to the kitchen when government guys enter the place.
Kathy the flake (metaphor)
Sally calls Kathy a flake: “She’s a flake and always has been”. When John has entered the diner Kathy was really stunned and the first thing she did was going to the kitchen and getting Charlie out as she knew he would not be glad to have just a guest in his diner. Calling Kathy a flake Sally means that she is spineless and can be easily ruled by others, taking responsibility or a strong personal position is not her trait.