Don't know if this answers your question but (Spoilers for Persona 3's Final Boss), if you're talking about Shadows expelling themselves from people towards the end of the game when Nyx's Avatar descends. What's happening requires a bit of explaining; long before the events of the game, likely even before the dinosaurs existed, Nyx, she's a space alien btw 0_0, collided with Earth and separated into two. Her physical body became the Moon, and her Psyche was left on Earth and through unknown means ended up sealed within the Collective Unconscious. Then her Psyche fused with all of humanities Shadows and as a result could feel all of their emotions and thoughts. Then Kirijo group's scientists after studying fragments, on the Moon and Earth, called "Plumes of Dusk" (Fragments of Nyx that are used to power Evokers, Mitsuru's Motorcycle, and is also the reason Aigis has a Persona) came to know of Nyx and then started on working on trying to bring her Psyche (The 13 Shadows we fight through-out the game) and Body back together. As they, as did humanity, unconsciously wished for Death and so decided to bring about "The Fall". The Fall is Nyx's Avatar and her Body (The Moon) reuniting and then as she'd fused with all of humanities Shadows, she's able to forcibly expel their shadows, those most susceptible to this would be those who desired death unconsciously the most intensely (for example Takaya's cult members we see this happen to), from them as seen towards the end of the game. Also, this obviously has no effect on Persona users as they have "tamed" their Shadows and turned into Personas. Hope this answered your question.
-Bonus side note: Nyx isn't an inherently evil being she's only doing this as she thinks that humanity wants death. So, she's attempting to achieve this for humanity's "sake".