Toriel

Before the events of Undertale, she was married to King Asgore and had a son, Asriel. When the first human fell underground, she adopted him as her child. The deaths of his two sons spurred Asgore to declare war on humanity, and as a result, she broke away from him, left her throne, and retreated to the ruins. Between the time the protagonist entered the Underground, they had seen several humans being murdered and their souls harvested by Asgore.