It was a day like any other in the Turtle's lair. Donnie was working on who-knows-what, Mikey was annoying him by messing up his experiments, Raph was talking to Chompy, Leo was watching TV, April was training with Splinter, and Casey was monologuing. Everything was just as usual, until April finished training and walked into Donnie's lab.

"Hey Donnie" She said as she entered the room.

Donnie turned his head to look at April. "Hey April. I was just experimenting with some chemicals. What do you need?"

April sat in one of the chairs scattered around the lab "Nothing. I just finished training and now I'm looking for something to do," she gazed around the lab until her eyes locked onto something she had never seen before. "What's that?" she asked, pointing at the object.

Donnie looked to where April was pointing. "Oh, that? It's nothing. Just a time-space warp detector I picked up on the technodrome a while back.

April gave Donnie a curious look "Wow. If that's nothing, I wonder what else you have in here,"

Donnie paused to think "What I meant is that it can't cause anything catastrophic. It hasn't even done anything since I snagged it off the Kraang,"

And with that, the device began flashing purple.

Donnie turned towards the flashing light. "Nevermind, something's happening. and in the main room of the lair. I suggest we check it out,"

Donnie and April ran to the main room to find a portal opening.

"As I suspected," Donnie said.

And then, Renet exited the portal.

Mikey entered the room, saw Renet, and ran to her.

"RENET!" He cried as he ran towards the time traveler. But just as he got close to her, she pulled out a sword and stabbed him in the chest.

"MIKEY!" Raph screamed as he charged at Renet, who blocked his attack with her staff. "HE TRUSTED YOU! HOW COULD YOU DO THAT YOU MONSTER!"

Renet pushed Raph away with her staff, and charged at Leo, who pulled out his katanas just in time to block, but Renet teloported behind him, and stabbed through his shell.

"GOONGALA!" Casey screamed as he leapt at Renet, swinging his hockey stick at her head, but she used her staff to zap him with lethal amounts of electricity before he could reach her. Knocking him back and stopping his heart.

"CASEY!" Raph yelled as he charged at Renet again. This time April and Donnie also tried to attack, but Renet held them all off with her staff. She then pulled out a futuristic gun, aimed it at Donatello, and fired a laser at him.

"DONNIE!" Raph jumped in front of the gun, taking the blow and saving Donatello's life, at the cost of his own.

"What is going on here?" Splinter shouted as he exited his meditation room. And when he saw his children and Casey dead on the ground, with Renet as the only possible suspect, he jumped at her. Renet shot at him, but he dodged the lasers and attacked, but Renet dodged with great skill. In the end, Renet shot a beam out of her staff, and Splinter was turned into dust.

It was down to the last three. Donnie and April agains the time traveling traitor Renet. Even though they had Renet outnumbered, it was a hopeless battle. Her futuristic weapons would overwhelm them no matter what they did, but they had to try. They had to avenge their team. April held out her bladed fan to attack...

And Renet shot her in the chest.

"APRIL!"

April's fan fell out of her hand and hit the floor with a loud clank. She fell, and Donnie caught her in his arms. Kneeling on the floor, holding her as she was dying.

Donnie looked into April's dying eyes. He didn't know what to say, he didn't know what to do.

"Donnie," April said. Donnie started to cry. And with that...

April died.

A silence fell over the entire lair, so great you could hear a pin drop.

Renet was the one to break the silence. She walked up to Donnie and aimed her gun at him. Donnie could tell her heart wasn't in it, but he didn't care.
He Stood up, and gave Renet a strong, terrifying, deadly glare.

"We trusted you, and you betrayed us. Now you die"

Donnie pulled out his staff. Normally, he would make an attempt not to kill his adversaries. Normally, he would use non-lethal methods, but not today. Such a heartless girl didn't deserve mercy. He extended the blade at the end of his staff, and charged at Renet, dodging the lasers from her gun as he went. And he had almost caught her,

when she teleported out of the lair.

Donnie dropped his weapon, walked back to where April's lifeless body was lying, knelt down, picked her up in his arms...

and cried.

He cried until he should've been out of tears, and then kept crying. He didn't even think about his brothers. They were nothing compared to the loss of April.
He didn't even say anything, he just knelt there, crying over April's corpse. April O'niel, the love of his life, was dead.

That night, Donatello buried the six of them in Splinter's meditation room, under the tree. He had pulled out floorboards, dug the graves, and even made the tombstones himself, but it was finally finished. Donnie's brother's, his sensei, and the love of his life, all buried under the one tree in the whole lair.
Donnie knelt in front of April's grave, in the very front of the small graveyard that had been built, and mourned the loss of his family, the only family he had ever known. And then, he made a promise.

"I, Donatello Hamato, will find Renet and all associated with her, and destroy them."

And from that point forward, Donatello found no mercy in his heart for the wicked.