Gao Zhao
In winter 507, Empress Yu died suddenly, and in early 508, her young son Yuan Chang (元昌), Xuanwu's only son by that point, died suddenly as well. Because Gao Zhao was exceeding powerful by that point, and his niece Consort Gao was Xuanwu's favorite concubine, it was largely suspected that Gao Zhao and Gao murdered them, but there was no conclusive proof. In 508, Xuanwu created Gao as Empress to replace Yu, despite opposition by Yuan Xie, and from this point on Gao Zhao became resentful of Yuan Xie.