Fan Casting Adaptational Jerkass in Sort by Tropes

Whatever the reasons, the writer(s) has seen fit to change the character's original positive portrayal, to make them more of a jerk. Perhaps the character was a Jerk with a Heart of Gold in the original work, but the adaptation failed to convey the "heart of gold" aspect. Thus, turning them into a total jerk. Or it could be due the adaptation being Darker and Edgier than the original, and the character's portrayal was changed accordingly.