It wasn't parchment's IME, it was the colour of his body. Just like Kin touched one of the symbols with her (gloved) hand to turn the shape
blue at the beginning. Parchment didn't create any IME fog, because he wasn't on the floor (which did, in combination with living beings create the fog). And the shape did then (when the familiar stopped touching it) turn green, because Kin's IME fog was still all around the room.
We haven't seen yet if Parchment has his own IME and whether it is the same colour as Kin's or a different one. Again, because he hasn't touched the IME-fog-emanating floor, nor have we seen him cast a spell or use a spell like ability.