Valve explains why Portal's Companion Cube had to die
When we cursed the heavens and asked tearfully why our beloved labradoodle, Cagney, had to die in a horrific snow plow accident, leaving behind her best friend (our maltipoo Lacey), the only answer we received was the stony ambivalence of a silent autumnal sky.
When we cursed Valve and asked tearfully why our beloved Companion Cube had to die by our own hands, Portal's writers calmly explained to Gamasutra that it was to develop a stronger bond with the Cube and teach the mechanics of the incinerator.
See how it's done, God? Was that so difficult?