I can never do that, either. I played through the entire Mass Effect trilogy as a Renegade (ruthless, amoral) Shepard once, and even then there came some choices where I was just like, no, I'm not doing that, I have to choose the Paragon option. Tried to play an amoral blood mage type in Dragon Age: Origins, and just never finished that playthrough. And in DA2, try as I might, I can't play anything other than Sarcastic Hawke. Currently, I'm playing an aggressive and abrupt Inquisitor in DA:I, and it's so hard. I'm gonna have to let him change a bit gradually, I think...