Tomas is excited by the prospect of bedding such an odd (and odd-looking woman).
The next time he is called to her apartment to wash the windows, they again drink wine and start kissing.
But when he gives her his standard "Strip!" command, she commands back: "No! You first!" (5.11.2).
Tomas is taken aback; he's used to being in the driver's seat.
Finally, he compromises with her.
For every piece of clothing that comes off of her, he has to remove one of his own. Similarly, every time he does something to her, she does the same thing to his body.
While they have sex, Tomas watches her very carefully, recording what is unique about her. He walks away with three distinct conclusions. (His conclusions are specific and sexual – you can read your book if you want to know what they are.)
He's psyched to have acquired another piece of the world for his own possession.