"I can see the Distortion, and the Distortion can occur to anyone. I don’t exactly know who coined the term “Distortion” for the phenomenon, but people just started calling it that at some point. No one knows how it works, but the experience so far suggests that this phenomenon is a manifestation of strong emotional desires and explosive surges of feelings."
- Moses, The Distortion Detective Chapter 1

Distortions (뒤틀림) are powerful, monstrous entities in the City. They are former humans who have been overcome by their emotions, typically haven given into the lulling words of a charming voice heard by no one but them. The process by which humans distort is referred to as the Distortion Phenomenon.

To be susceptible to distorting, one must experience the complete breakdown of a firmly-held belief in a massive personal shock. In this state of exceptionally heightened emotion, the mind "crumbles". For example, victims of the Distortion are frequently shown to have been working for a goal meaningful to them before realizing it cannot be carried out in a sudden and dramatic event.

To be targeted by the Distortion is to be spoken to by Carmen herself. Someone undergoing the Distortion process will hear a warm, alluring voice unable to be heard by anyone else. The voice will speak to the target about their present situation and prod them into giving into their heightened feelings, using specific words meant to make them focus on their negative emotions.

If the target chooses to embrace these feelings, agreeing with Carmen's discernment of their life, they "consent" and therefore Distort. Distorting includes transforming into a being which reflects the person's ultimate feelings and desires.

information copypasted from Library of Ruina and Limbus Company wiki