It seems that the Underground Man tried to humiliate Liza, acting out of spite.
There are some accessible introductions online (YouTube has a couple of seminars by Prof. Michael Moir, lectures from Dr. Gregory Sadler; there’s also an article by Prof. Alexey Vdovin on a Russian educational project Polka.)
What is the hero like? According to the Underground Man
all “direct” persons and men of action are active just because they
are stupid and limited.
This hero is unable to commit to a certain line of behavior. Systems are restrictive, and he cannot validate them anyway (all values are subjective, and there’s too much information). Apparently, he didn’t develop any solid identity (regrets that he can’t be called even lazy and can’t be “positively defined”).
Without any framework, he often relies on internal feelings and impulses, like pain and pleasure. Moir points out that his bureaucratic work doesn’t give an output to his individuality, so he often daydreams. Then he realizes that even these dreams came from literature (like a play Masquerade).
He’s very sensitive and attentive to how he looks (worries about a yellow stain, argues with an imaginary audience, and so on). He’s also sensitive to the issues of power and status. Moir says that to this character “other people are basically mirrors”. So the Underground Man seems very narcissistic. Here’s what I learned from a psychologist’s newsletter (on the Dark Triad traits which comprise narcissistic ones):
People high on the Dark Triad are more likely to use immature defense
mechanisms (r = .53), including passive aggression, denial, and
autistic fantasy (e.g., responding to emotional conflict with
excessive daydreaming)
So we have bad coping skills, a lens of power, and “no commitment”. How will this work together?
The first time he meets Liza, the Underground Man is well dressed and lectures her on morality. Then he worries that she’ll realize that he basically catfished her. He tries to daydream himself out of it imagining how he saves Liza, and she falls in love with him.
But when they really meet, he is pitied. By this low-status girl. Who is a prostitute.
This really upsets the Underground Man.
The epigraph to the Part II comes from a poem by Nikolay Nekrasov describing apparently a former prostitute who cries about her past sins before the narrator. But Prof. Vdovin points out that exactly the opposite happens in the book: it’s the Underground Man who weeps and cries. Their roles were reversed. And if she’s a heroine, then who is a person lacking moral commitments here?
Now she has a higher status, and the Underground Man reacts. The hero not only doesn’t save her, but by giving her money, he basically pushes her back into the role of a prostitute.
Liza sees his manipulations for what they are and doesn’t want to participate:
She realised that my outburst of passion had been simply revenge, a
fresh humiliation, and that to my earlier, almost causeless hatred was
added now a personal hatred, born of envy...
After the intercourse, the hero is immediately “oppressed by her being here” and wants to be alone. He gives her money, but says that it was “a product of the brain, of books”, not “an impulse from the heart”. This probably means that he’s not evil but playing a role of an evil person, he does what seems consistent with the role. In a minute, he regrets it and calls her “but in a low voice, not boldly”. Again, he cannot commit.
