The Sceadu were an aggressive race of beings made of anti-photons. They could only exist in the dark. Having all but destroyed the Prin, they hunted down the last Prin to the planet Earth where he was hiding, disguised as a human who lived in a house that was lit all year supposedly to celebrate Christmas.
The Sceadu were trapped in the Prin ship. It blasted off and the Eleventh Doctor took the Prin to a safe place to live. (COMIC: The House of Lights)