During the making of Portal 2, playtesters actually complained that GLaDOS was too mean — the devs had to tone her down into something more comically passive aggressive

Portal was a fantastic, ground-breaking puzzle game in its own right, but what would our cube-stacking, wormhole-blasting journey through the abandoned Aperture Labs have been without the scathing, autotuned commentary of GLaDOS undermining our every move? This rogue AI’s increasingly wicked intentions and equally witty attitude made Portal 1 and 2 the hilarious, and at times horrifying, emotional rollercoasters that they were. GLaDOS made such an impact in the first Portal, that we can think of few moments in games more menacing than her vengeful rise from the dead at the start of Portal 2.