Sans (Guns, as the author calls him) became more kind and sensitive, and also got post-traumatic stress disorder. Is paranoid. As a child, while playing with little Papyrus, he was called by his father, who wanted to test the pills containing Resolute on him. The pills contained only three percent human determination, but even that was enough to awaken tremendous power in Sans. He had fluff on his hood and "war paint" (black lines running horizontally to his temples and vertically down). 