Asmodeus gave us the strongest statement of his purpose so far. His job is to do evil for Aksinya. Her response follows.
Aksinya’s eyes darted from one side of the room to the other, “But I don’t want to do any of that.”
“So long as you accomplish evil, I will be pleased. Choose the evil you will do, and do it well. I only remark the evil that will occur if you fail at your part of the bargain.”
“I made no such bargain. I contracted you to be my servant. That was our agreement.”
“There you are wrong, Countess. You contracted to me using a part of your body as a surety. The contract was to me, the demon Asmodeus. I agreed to do your evil work in the world. That is our agreement—to do your evil work in the world. Since you have chosen to have no plan to pursue evil, I am providing one for you. I am happy to do it. I must confess, I was very pleased with how our relationship started. I am not as delighted with how it has progressed.”
“I hate you, demon. God will surely punish you for every way you torment me.”
“God will surely punish you, Countess, because all the evil I do is in your name. In fact, I myself commit no sins—it is you who sin. I am simply a tempter.”
“Get out. Get out of my room and torment me no more.”
“I will leave you for now. You understand what you must do, Countess.” Asmodeus slipped off the bed. He backed to the door and out of the room.
Aksinya waited a few minutes before she moved. Then she ran to her door and yanked it open. The demon was gone. She took a deep breath and leaned against the jam for a while. Then she closed her eyes and mouthed a prayer. She crossed herself. That small action hurt her heart. She couldn’t hold back a whimper and glanced around. She was afraid she would hear the demon’s laughter come out of the close darkness.
After a little, Aksinya closed her books and went to Natalya’s room. She didn’t even finish the work she was supposed to do. With Natalya, she reviewed her lady-in-waiting’s German work and spoke German with her for an hour. Then she went to bed.
If you didn't understand the demon's purpose, there can be no question now. "Choose the evil you will do, and do it well." Then, the bargain. The point is that evil will occur if Aksinya fails to uphold her part. We will see the evil in the future, for now, this is a threat and a foreshadowing.
Did you wonder at the demon's claim. He claims not to sin--that he is only a tempter. This may or may not be true. Aksinya, in any case, bears the brunt of the sins the demon accomplishes in her name--that is his purpose.
Aksinya reveals her own desires after the demon is gone. The act of crossing herself causes her physical pain. This is presented as real physical pain, but we can't be certain that it is not psychological.
Then the end, Aksinya goes to help Natalya. She neglects her own work for Natalya's sake. I'm not certain the demon expected her to do this, but the point is that she takes her evening to help Natalya. You might wonder at the demon's purpose.