7. The Companion Cube Has Corpses Inside (Portal)
The Weighted Companion Cube amassed a seemingly instant fan-base following its amusing appearance in the first game, with the inanimate object becoming oddly personified, something that becomes a whole lot more ironic with this theory. In fact, the theory suggests that the cubes are filled with the remains of failed, dying test subjects who came before our protagonist, Chell. The evidence begins with the console achievement "Fratricide" you receive for dumping the cube into a furnace in the first Portal - an odd choice of words for an inanimate object, no? - as well as GLaDOS' insistence that if the cube speaks, it should be ignored. The Portal comics also depict a man talking to a cube, and it appears to talk back, but perhaps most compellingly, the cubes are never faced with the same particle disintegration that almost every other item is at the end of a test chamber. These forcefields allow organic matter through and stop any contraband passing to the next stage; presumably this never occasions itself for the cube because if one tried to pass through with it, the dead body would fall out as the cube disintegrated.