Those murdering, sweet talking turrets have a song in their hearts, and if you’ve beaten Portal 2 (or found the secret vent), you’ve heard them sing their sweet, siren song. But why do they sing, and where did they earn their singing chops? The answers are revealed in this mini-comic, which you can view here.

Oh, and in case you never found the secret vent and watched the turret quartet singing their microchips out, here ya go: