So this au is called AstroNindroid!
In this au, Kai and Nya get invited by their inventor aunt to see a new security robot. They take the others with them, and they meet up with the aunt (who we will call Cath).
The others follow Cath to a lab where the robot would do a demonstration. Unfortunately, there was a malfunction at the demonstration, and Kai died. Cath, feeling guilt for causing her nephew’s death, decided to make a robot copy of Kai. She put everything to thought: memories, replica of fire powers in machinery, looks, even behavior. The next day, Kai wakes up and everyone is happy to see him.
But coding a robot to be human who died does not always go as plan
No one but Cath and the employees knows he’s a robot. As the days go by, Kai starts to feel weird and act less like he usually would. The others, and himself, are getting concerned. Then one day, Kai goes flying into the sky with his new fire powers. When he returned to the place he and the others were staying at, he heard a conversation between Cath and an employee. Kai asks Cath what’s wrong, in which she responds coldly.
The others come in, and Nya asked where Kai has been. Cath tells Nya to not talk to it, and confessed that this Kai is a robot. Nya is now in grief, realizing her brother is gone for good. Kai tries to comfort her, but she tells at him, telling him he isn’t her brother and just a copycat. Nya realizes what she said, but Kai ran off before she could apologize.
So Kai, now questioning who he is, leaves Ninjago island and goes to the lighthouse he- No, the real Kai and his friends went to and found Dr. Julian. There, Kai finds a shut-down Echo. Kai thought about Zane sharing his power source with Pixal. Maybe Kai could do the same. Except Kai’s power source was just a ball of unknown energy. However, the ball of unknown energy powers up Echo from afar, and he wakes up.
Echo goes: “Hello! :D” and Kai goes: “Oh FSM, oh fck, what did I do? How did I do that?”
So Kai decides to take Echo to Borgs Industry, then Kai will travel back to the lighthouse by himself. But Kai gets confronted by the other ninjas. Nya apologizes for yelling at him, and she wants to do whatever she can to help him now. Kai says it’s best if he goes away, but Nya pulls a Lilo and Stich (along with Maya and Ray who show up after Nya calls them).
So now Kai goes by the name Viorel and changes how he looks a bit. He sometimes feels like he is only there because he’s a replacement. He’s scared of Cath because he fears that she will dismantle him and put him a junk yard one day. But he has moral support from Nya, Echo, Pixal, and the ninjas.
Nya is now the big sister and protecc her baby brother when he feels scared. Viorel doesn’t want to be a ninja, so he becomes a samurai instead, Nya training him.
