Changeling
From Tardis Wiki, the free Doctor Who reference
Changelings were individuals controlled by the Graske that mimicked a lifeform and sent the real one to Griffoth. They looked almost exactly like the originals, but their eyes flashed a greeny-gold colour occasionally, hinting at their true disposition. Changelings appeared to behave in just the same way as the originals, so that hardly anybody suspected them. The Graske needed to keep the originals alive in order to sustain the changelings. A Graske created Changelings for a Slitheen, a street Urchin, a Mum and a Dad before they were returned home from Griffoth. (GAME: Attack of the Graske)
