A character in their late 20s stalks, fantasizes about, and later has sex with a traumatized and extremely vulnerable homeless 18 year old high school student. While she seemingly consents and he stops when she passes out, the action is predatory.
The main character is 18 and the main male character is in college. His age is never stated, but he seems to be an intelligent graduate assistant, so he's likely in his EARLY twenties.
An adult man in a doctor role has a sexual dream about a teenager he has been following. They later have sex in the real world, and it is shown to be consensual.