A little bit of a preview/plot bunny for a full-length AU I'm working on

For the gang it was a regular trip to Lyoko, Odd had been divirtualized leaving Yumi and Ulrich to protect Aelita against the monsters. "Impact!" UIlrich yelled taking out a Blok while Yumi felled a Krabe. "All clear, get Aelita to the tower" Jeremie said over the intercom. The pair nodded to her gesturing towards the tower but then something appeared, something Jeremie didn't see until a second too late.

A boy, with dark hair and determined eyes rushed towards the trio with his sword brandished. He was in an outfit Aelita recognized but couldn't place. Yumi and Ulrich stepped in front of her weapons drawn. "Stay away from her" Yumi warned but that only seemed to make the boy wilder as he sent a wave of energy from his blade at her. Ulrich only had enough time to call her name before the blade went through his stomach.

Jeremie was in a panic, Aelita was alone with the boy and if she got devirtualized she would be gone for good. The elf girl trembled backed into a rock. But the boy didn't attack, he thrust his weapon into the ground next to him and fell to one knee bowing his head respectfully.