The end.

Eventually they manage to have him meet with Kaeya. Although the presence of WuXin reborn does have an effect on XinLan, it is not enough to bring him back to normal. It would take time anyway and he isn't cooperative on the matter.

When they return to see XinLan in the cell, he decides to do the only thing he has left to do, since now he is in trap and can't go anywhere.
He waits for both Lani and Qi to be present, he demands them both to be, pretending he has to tell them something. Then, in a fraction of a moment, he summons his own special weapon and literally stabs himself to death in front of their eyes. «Now you will know how I feel…» he gasps. «Now you will know what you have caused me…»

Shortly after his body collapses on the floor, a fire catches it whole and reduces it in ashes.
Lani didn't even make in time to get inside the cell before the fire happens, to try to do something to save his son.
What nobody would have expected though is that in all the ashes, a newborn baby starts to struggle and moan desperately.

Not wanting the matter to be known by the others, Lani takes the baby in arms and looks at Qi, asking him to make them invisible. Done that, Lani runs outside and teleports to his lab, after asking Qi to tell everyone that XinLan killed himself but to avoid to say that he was reborn from his ashes, like a phoenix. People will easily guess, but Lani wanted to at least try to hide it, for the safety of the baby.