Gael is a tragic hero, if you think about it. He literally journeyed to the Ringed City to fetch the blood of the dark soul so that the painter could paint a new world, that everyone would abandon this dying one. His soul description literally states that he knew he was not going to withstand the corruption of the Dark Soul, because he wasn't a Champion. He fully expected himself to be corrupted, and he expected you to be the one to put him down, retrieve the blood of the dark soul, and return it to the painter. Gael is as much of a hero as you are.