Bingwang Immortal, the ancestor of the Profound Sect who was said to reach the Mahayana Realm (Void Refining Stage) and the most powerful cultivator who was said to reach the ascension stage. It was just that he had failed ascension due to two people scheming against him and dying in the end. But it seems after he failed to ascend, he didn't die right away, and his soul was transferred to Hei'An's clone living as An Juejing.
It is just his state as An Juejing: Sometimes his original soul will wake, and most of the time he will be An Juejing, a new person with no hint of being the ancestor of the Profound Sect. His awakening only got frequent when they met the Divine One at the borderlands.
An Juejing's uncontrolled attraction towards this man made Bingwang Immortal's soul more powerful than before until the innocent An Juejing merged with him, leaving only Bingwang Immortal in this body.