Common elements in 'erotic trap fiction' include the initial allure. This is what draws the victim - like a character's physical beauty or a false sense of a great opportunity. Then there's the element of inescapability. Once the trap is sprung, it becomes difficult for the character to get out. There are also often hidden motives among the characters involved. For example, one character might be after revenge or some sort of gain through trapping another in an erotic situation. The genre also often plays on the characters' lack of knowledge or misinformation which leads them into the trap.
One common element is the use of seduction. Characters often use their charm or allure to draw others into the trap. Another is the element of secrecy or mystery. The nature of the trap is usually not fully revealed at first. For example, a character might be invited to a secluded place with the promise of a romantic encounter but end up in a more complex and entrapping situation.
Well, in 'erotic trap fiction', a typical element is the power imbalance. There is often one character who holds more power over the other in the context of the erotic situation. Also, the setting plays an important role. It could be a dark and mysterious place like an old mansion or a seedy underground club. These settings enhance the feeling of being trapped. Moreover, the characters' internal desires and weaknesses are often exploited to create the trap. For instance, a character's loneliness might be used to draw them into a relationship that turns out to be a trap.