>>213903891 (OP)
Casca settled on Guts because Guts was actually real. He was a real person who had real feelings and was not an aloof demigod with no capacity to view other people as human in the same way that he was. Griffith's desire for companionship was not based on desires of the flesh, but on a sort of fragile solipsism, he needed to know that there was someone besides him in the universe who possessed a Will.
Casca doesn't have a Will. At every point in the story, she is moved, she does not move others. Only Griffith, and Guts, are truely self-moving souls, and thus to Griffith only Guts truly represented his potential equal, which is the only sort of person he could ever meaningfully interact with in a way beyond master and slave. Casca was not in love with Griffith, she was simply transfixed by him, it was in no way reciprocal--which love must be, if it is to be real.
