Phycomimictry

When one imitates others mood and/or personality when around them.

For example when one is speaking to a toxic person and the toxic one calls the other a homphobic slur and they call them one right back.

Often requires a self diagnosis mostly due to the fact that this shit isnt a real thing yet and cant be diagnosed.

Grandma: oh your such a sweet boy come here darling.
Kid: i love you so much grandma your amazing.
Docter: son, you have phycomimictry