Logan: if Logan is around Deciet for too long his vision will go all foggy and he would be able to think straight. Also gets a bad headache.
Lying clouds judgement.
Roman: Roman becomes more egotistic and insults the others more.
Lying is used to feed the ego.
Patton: Patton is probably the worse, he loses his ability to speak and it's like he's not around.
Lying cancels morality.
Virgil: Vigil becomes more anxious that normal. He is jumpy and very observant. His flight of fight reflex could activate at any time.
Lying worsens anxiety.

Hello Ik I like dropped off the face of the earth but I'm back!!
If u wanna see any headcannons plz feel free to share them in the comments. Okie bai
-Buni