Of course, the Thunder Emperor had given her a new name to hide her identity. He was not yet powerful enough to protect her from people like the Burning Sun Ancestor, who would want her dead at all costs.
He had named her Ember.
It was a simple name without any special meaning, but the Thunder Emperor thought it was fitting for her. In the future, she could regain her true name once he had taken care of those who wanted her dead.
To ensure that her true identity was not discovered, the Thunder Emperor made sure that everything was perfect.
He found a rare art in the sect called the Blood Forging Art. This emperor-grade technique was particularly attractive to the Thunder Emperor due to its unique capability: it could disguise one's bloodline and create a false one.
The Thunder Emperor learned this art and used it on the girl so that her bloodline would match his and that of the Waking Moon.