Author's Note: Here is the final part of my first Ben 10: Ultimate Alien fanfiction. Thank you very much to everyone who has read it (especially the ones who left reviews and put it one their favourites list). I am very glad you liked it. Thanks again to Eternal-Night-Ride, benlie-gwevin-fan1 and CrystalQuirt who inspired me.

"I've got to stop him" said Ben firmly. He began to dial the Ultimatrix again.

"Use caution, Ben" Azmuth advised. "The antidote has only just been administered so none of your forms will be at full strength."

"He's right Ben" Julie agreed.

"Okay I got it" he replied before transforming again. "Jetray!"

Aside from being paler than normal, the Aerophibian looked to be in good shape. He flew out of the room and down the stairs just as Sardu was starting to make his way up.

Jetray tackled him head-on, propelling them both back out of the exploded door and onto the front lawn. Sardu dropped to the grass and rolled away as Jetray soared up into the air.

Turning around, the manta-like alien fired neuro-shock blasts from his tail. Right away he saw that his blasts were weaker and slower than usual. His opponent dodged them and returned fire with his blaster pistol. Normally he could have easily evaded them but his speed and reflexes were still dulled. The first energy bolt missed, but the second scored a glancing hit that sent him into a tailspin. He managed to land on his feet but a third shot hit him directly and he fell onto his back. Dazed he looked over at Sardu to see him pointing the blaster at his head.

Before he could pull the trigger, a glass tube flew through the air and hit the barrel of his pistol. The tube broke and splashed clear liquid over the blaster barrel which immediately started to hiss and smoke as the liquid ate into it.

Sardu angrily hurled the ruined weapon away and looked up to see Julie standing in the doorway with a determined look on her face. In one hand she was holding several test tubes from Azmuth's chemistry equipment. Her other hand held another tube ready to be thrown.

Jetray fired a neuro-shock blast from his eyes, hitting his enemy in the torso. Sardu stumbled back as Jetray stood up, transformed into Swampfire and hurled a handful of seeds at Sardu's feet. The seeds immediately sprouted into green vines that wrapped around him and immobilised him.

Julie ran up to Ben as he de-transformed. He swayed unsteadily on his feet and she supported him. "Are you okay Ben?"

"Yeah I'm okay" he replied as he recovered and stood more firmly. "Thanks for your help."

"You're welcome" she said with a fond smile.

Ben turned to Sardu and glared at him. "Okay talk. Why did you infect me with that virus?"

Sardu glared hatefully at them but then his face twisted into a fiendish smile. He tested the vine binding his left arm, finding it weaker than the others. With a firm tug he snapped it.

Ben moved in front of Julie and raised a hand over the Ultimatrix, fully expecting him to draw another weapon. Instead he produced a small white pill.

Azmuth came running up. "Stop him!" he shouted. But it was too late.

Sardu bit down on the pill and sneered at them just before he slumped lifelessly. As they watched his skin turned coal black and his body dissolved into ash. Within a few seconds all that was left of him were his clothes.

Ben looked down at the Galvan scientist. "Okay Azmuth, did you know that guy?"

The three of them were now in the living room. Ben and Julie sat together on the settee while Azmuth stood on the table in front of them.

"He was a member of Abyss" he replied grimly. "It's a fanatical cult that believes the universe and everything in it is somehow fundamentally flawed. They believe that it must be completely destroyed so that a better universe can replace it."

And there was a time when I would have agreed with them he thought darkly as he recalled his first meeting with Ben Tennyson and how he had been willing to let the universe be destroyed. Ben had changed him then, had renewed his faith in the inhabitants of the cosmos and he was deeply grateful to him for it.

Not that he'd ever admit it of course.

"That's why they wanted the Codon Stream destroyed" he said aloud. "It can be used to re-create any species that has been wiped out. Abyss considers it to be an obstacle to their goal."

"You knew this" said Julie in disbelief.

"I suspected it" he replied. "I didn't know for sure until I saw that cult member."

"So, what now?" Ben wondered. "If that guy was part of a cult then won't his buddies be looking to finish the job?"

"I will notify the Plumbers and they will begin a crackdown on Abyss" he replied. "In the meantime you needn't worry too much. Now that this plan failed they won't try it again. Nonetheless you should stay alert."

"Now I must return to Primus. I need to make some improvements to ensure this won't happen again."

"Thank you for saving Ben Mr. Azmuth" said Julie warmly.

"Yeah thanks Azmuth" Ben agreed.

He started to say how he'd only helped them to save the Codon Stream but he hesitated. Finally he said simply "you're welcome" before teleporting away.

"I'd better call Gwen and Kevin to let them know I'm okay" said Ben.

"Good idea."

He started to reach for the phone but then hesitated. "So what'll you do now that I'm all better?"

She shrugged. "Well my parents already gave me permission to stay over for tonight, so I guess I'll stay." She smiled as she added "if it's okay with you."

"It's totally okay" Ben said immediately. His expression then turned sheepish as he realised maybe he'd said it a little 'too' eagerly. Julie giggled softly.

"Thanks again Julie" Ben said; his voice completely serious now. "You really saved me today, twice. First when you got that smoothy cup, and then when you stopped that guy before he shot me. You're one of the bravest people I know and there isn't any girl I'd rather be with."

"Oh Ben" she said softly, touched by his words. She leaned forwards and gave him a light but affectionate kiss.

Light years away, Marus once again stood before Rirtu as he delivered a report to his superior.

"Sardu failed" he said coldly. "Not only does the Codon Stream remain but now the Plumbers are moving against us."

Rirtu nodded. "We will have to go further into hiding" he said. "But this is only a setback, nothing more."

He dismissed Marus and settled back into his chair to think. For now they would have to focus their efforts on survival, but he had no intention of forgetting about Ben Tennyson, not at all.

The end.