At a young age Tantai Ruonan already displayed extreme talent that even exceeded her own father when he was younger. She was even able to use the Trident and was accepted by it. Her cultivation was also exceedingly high, so she became famous across the Nine Worlds as the True Martial Goddess. Many people held her in high esteem and thought that she would have the best chance of becoming the next Sea God after her father.
However, True Martial Sea God didn't wish for his daughter to walk on the same path as him in the future and wanted nothing more than for her to be free of the Sea Demon's bloodline, to be able to travel across the Nine Worlds without restraint. Alas, Tantai Ruonan's divine bloodline was extremely powerful, even True Martial Sea God had no method to sever it.
True Martial Sea God went to meet Immortal Emperor Min Ren's teacher - Dark Crow - in order to search for a method of severing. They made ample preparations and worked together with Immortal Emperor Min Ren to blind Old Villainous Heavens's eyes and removed all related karmic fate. Finally, working together, True Martial Sea God and Immortal Emperor Min Ren managed to sever Tantai Ruonan's bloodline and disconnected her from the Sea Demon Race.
In truth, however, Tantai Ruonan became Dark Crow's disciple. Dark Crow spent painstaking efforts to train her, no less than on Immortal Emperor Min Ren. Tantai Ruonan was already exceedingly talented, so after staying with Dark Crow and enjoying his full tutelage she became fully capable to become an Immortal Emperor. Nevertheless, she didn't become one.
Instead, Tantai Ruonan joined the newly created White Crane Legion - one of the Four Legions of Dark Crow. Moreover, she became the Legion's first commander with only Immortal Emperor Min Ren and Dark Crow above her.