Don't start playing the video until you get to Cole's POV. Won't make sense until then.
Lloyd
Several years after Kai's death in an unexpected eruption at the Fire Temple, while he was recovering from severe injuries, a new crime lord popped up in Ninjago City, by the name of Phoenix. The person took over every kind of crime within the city; drugs, prostitution, gangs, all of it, but overall, crime was down, and other gangs had been crushed since the person came roaring onto the scene, only that he would not tolerate selling to kids, or the harming of those he considered his property. No one had seen what Phoenix actually looked like or heard what he actually sounded like because he had a voice modulator in his helmet. The team and I had attempted to hack into the computer systems but found ourselves blocked each time. I even attempted to break into Phoenix's hideout a couple of times but ended up having to run off from their attacks each time. Out of nowhere, Nya yelled out in alarm from the garage within the mountain the monastery of spinjitzu was built on.
"Guys! Someone is hacking the computers in the garage! Hurry!" Nya called out over the intercom.
We all ran for the hidden elevator and made our way down to the garage. As we joined Nya, we could see letters and numbers flashing across the screen before a video of the Phoenix popped up on the screen.
"What the hell?" Cole whispered.
"Ninja, I hope you find this message well," Phoenix said calmly.
"What do you want?" I asked, stepping forward.
"Nothing much, Green Ninja. I intend on performing at next week's concert honoring your fallen Fire Ninja. I have no intention of harming anyone there because I care for my city, but I want your guarantee that I will not be arrested. The concert is neutral grounds for both Light and Dark forces. Do we have an accord?" Phoenix demanded.
"You have our word on our honor as Ninja that we will not make a move against you at the concert next week, Phoenix. But if you break the truce, you will face us personally," I growled.
"As if any of you could take me on," Phoenix seemingly sneered through his voice modulator before ending the video and backtracking his way out of our computer systems.
"I do not see any trace of him in our systems...Running diagnostics now..." Zane said shakily as he seemingly froze in place.
"Why do you think Phoenix wants to perform at the concert next week, Sensei?" Jay asked nervously.
"I...do not know. One can only hope that Phoenix's agenda does not end up destroying Ninjago," Wu said grimly as he stroked his beard.
Cole
A week after Phoenix hacked into the monastery's computer systems, everyone was gathering in Ninjago City for the Day of the Departed concert. Nya's parents were somewhere in the crowd, and Misako and Garmadon were also present. The others, Wu and I, were at the front of the crowd. The first several acts had come and gone with no sign of Phoenix. Finally, Dareth announced that it was time for the last act as the lights on the stage went out. A hush quieted the crowd as a haunting melody started up from the stage. Tiny, brief glimpses of flames whipped up on the stage for a fraction of a second in various positions. The music stopped for a moment, and the crowd held its breath before the lights came on dimly to reveal Phoenix and his band. Phoenix had a modified helmet revealing his mouth and lower jaw. We saw that Lloyd's reports of Phoenix actually having wings and tail feathers were true. Whether or not they were real was the question.
"Taken what was mine..." Phoenix sang almost sadly. "Stolen."
"What the hell?" Nya whispered.
"Buried underneath the very promise..." Phoenix continued. "He made."
"What kind of crime lord sings something sad?" Jay asked.
"One with a sad beginning," I answered.
"Standing by the flames..." Phoenix sang. "You stoke them."
"Um....guys....my sensors have started running voice recognition," Zane noted.
"And wonder why the end..." Phoenix sang as his mouth curved into a smirk. "Always seems so far away."
"Follow, and you will see," his backup singers added as the music shifted briefly.
"What do you mean, Zane?" Wu asked.
"You can't erase me," Phoenix sang, seeming to turn his attention toward us. "Lost and found..."
"For familiar voices, my sensors will trip and start running voice recognition," Zane fretted.
"I crawled out of the river," Phoenix sang.
"Why did you have to go?" the backup singers added.
"Of the river," Phoenix repeated.
"W-w-why did you have to go?" the backups repeated.
"This is getting weird, guys," Jay whimpered as he hid behind me.
"Sealed tight...to the end..." Phoenix sang in a soft harmony. "With all my broken bones..."
"I have a bad feeling," Lloyd noted as Phoenix slowly reached up for his helmet to start unlatching it.
"What do you take me for?" Phoenix crooned as the clink of him unlatching his golden-stylized helmet echoed over the music. "What do you take me for?"
"Is he really taking off his helmet?" Nya asked.
"It appears so," Wu noted before the music changed.
"I'll never be, what you dreamed," Phoenix sang loudly as he ripped off his helmet, revealing his true identity...as Kai, "Escaped from your reality."
"FUCKING WHAT?!" Nya screamed in shock.
"Open my eyes...now I can see," Kai sang as he looked at Wu with a nasty glare. "What lies beneath."
"Kai's alive?" Jay gasped in shock.
"You see, I'm gone...and who I was," Kai sang as he gripped the mic and pulled it from the stand. "Will never be..."
"Apparently. I thought he died I that eruption...There wasn't anything left of him..." I said numbly.
"Consider it..." Kai sang with a sneer as he continued to glare at Wu. "A Death in the Family."
"It doesn't sound like he wants to rejoin us..." Zane said. "It is him. My voice recognition just confirmed it."
"A Death in the Family," Kai said before he placed the microphone on its stand as the music slowly changed. "Consider it...A Death in the Family."
"We have no chance of getting him back..." Nya practically whimpered in shock over the screaming crowds.
"Air in my lungs..." Kai sang softly. "Through chamber smoke."
"Is he talking about his weapons?" Lloyd asked.
"I've come undone..." Kai sang as he gripped the mic and closed his eyes. "I'm the...only hope."
"Only hope for what?" I asked myself.
"Perhaps he is talking about the people of Ninjago City. They have been safer since he came on the scene in his new alter ego," Zane theorized.
"And yeah, you should fear me..." Kai sang as he folded his wings tightly, and the music shifted. "And yeah, you should run..."
"Run from him? Is he talking about villains or us?" I asked.
"I believe he is talking about us..." Wu answered.
"I'm tired of dreaming..." Kai sang quietly. "Of what should be done."
The music paused for a moment before flaring up like the strike of a match. The second the music restarted, flames flared up around Kai as he flared out his wings and tail feathers in a display of power.
"I'll never be what you dreamed," Kai sang loudly. "Escaped from your reality."
"I just want Kai to come home..." Nya said sadly.
"Open my eyes...now I can see..." Kai sang as he sneered down at Wu. "What lies beneath."
"Why does he keep looking at you like that, Sensei?" Jay asked.
"You see, I'm gone, and who I was..." Kai sneered as he sang. "Will never be..."
"I will tell you once we return to the monastery. It is not safe to tell here," Wu said tensely.
"Consider it..." Kai sang as he set his wings and tail feathers on fire. "A Death in the Family!"
"Is this related to why we think he died? Is that why he says to consider this his true death?" Lloyd asked himself.
"A Death in the Family!" Kai sang as he lazily flapped his wings. "Consider it...a Death in the Family!"
"It is likely, but why would he come back this way?" I asked as the music shifted again and started to fade out.
"Standing by the flames, you stoke them..." Kai almost whispered into the mic as his flames went out. "And wonder why the end always seems so far away..."
As Kai's voice and the music faded into nothing, Kai snapped his fingers and used his flames to teleport himself and his band, along with their equipment, away from the concert. Everyone was left in shock.
Jay
After Kai vanished, it was complete pandemonium. The rest of the team and I made it back to the temple after escaping the crowds. Lloyd's parents were there, and so were Nya's.
"Wu, what happened to my son?" Nya's mom practically snarled.
Wu looked at us sadly and turned away to face a window looking towards Ninjago City.
"When Kai was healing in the Fire Temple in his chrysalis, I had learned the true nature of what he was undergoing. He was becoming what you saw tonight. With his exceptionally strong abilities and stronger-than-normal connection to the Underworld...I could not risk him completing his transformation and going mad, so I triggered the Eruption. I never thought that he would be able to survive it, or that the Fire Temple may have sent him somewhere to protect him," Wu admitted before he was suddenly blasted against the wall by Nya.
"You...You made me think my brother was dead for 5 fucking years because you were scared of him getting stronger?!" Nya screeched as tears started rolling down her cheeks.
If ya'll want me to turn this into a full story, let me know in the comments. It won't happen until May at the earliest as I am in college and working almost 30 hours, but I'll be getting some free time then with only one class over the summer