The reason why Lilac wants Zhi 'an is because it signed an agreement with Tang. Lilac is a character in the TV series Lanhuaxiang. Lilac was originally a beautiful, intelligent and naive art college student. A merciless fire destroyed her home. The protagonist Tang was seriously ill and disabled because of the original formula, so he could not have children. In order to keep the oath he made with his wife that he would never take a concubine, he secretly agreed with Lilac to give birth to her daughter Tang.