I have an idea for a SCP, idk if it exists already, it's not that interesting too, but it's pratically a humanoid being that can interact with any other SCP without suffering any of its effects (if it has any), good, neutral or bad, like, it can hold cup of joe and put it down at any time it wants, when interacting with 999 it won't feel anything.
Some SCPs will refuse to do any contact with it, others claim it is boring to be with it, and may express some form of fear and/or hatred towards it, but won't be able to do anything to it.
Feel free to add anything or even make a log on the foundation.