One fascinating creative choice of Terminator 2: Judgment Day was how the antagonist of the first film, the T-800 (Played by Arnold Schwarzenegger), was turned into the guardian and protector of John Connor in the sequel. As it turns out, James Cameron considered having that switch go both ways. At one point, Cameron actually considered Michael Biehn, who played Sarah Connor's guardian (And eventual love interest) Kyle Reese in the first film, to play the sequel's antagonist, the T-1000, before Robert Patrick was ultimately cast. This would have been because the machines had gotten ahold of Reese's DNA in the future and felt a familiar face would be a way to get close enough to John and Sarah to kill them. While this didn't happen, Biehn did ultimately reprise his role of Kyle Reese in a dream sequence that was cut from the theatrical film but restored for the Director's Cut version.
Interesting. I wonder how the sequel would have looked like with bihen as the bad terminator. He did end up playing the villain though in the abyss.