DISCLAIMER: I do not own Prototype or the Avengers.

The doors of the mansion were ripped off their hinges, and Mercer charged in, surrounded by creatures infected with the new strain of the Mercer virus, which now included Symbiote matter, much greater strength and a very strong healing factor. These creatures were still only grunts, but they were much more powerful than the ones that had attacked the mansion before.

Wolverine started slashing the creatures apart, while Spider Man and Thor started striking them back. Mercer shoved his way through the crowd of brawling heroes and infected, glaring at the man in the wheelchair who sat at the base of the stairs. Mercer placed Juggernaut's helmet on his head, and was instantly safe from the mutant's mind control.

Wolverine jumped onto Mercer, stabbing him, but Mercer slashed Wolverine through the stomach, tearing up his flesh but not breaking his Adamantium skeleton, and kept walking. Ice Man sprayed ice at Mercer, but Mercer was almost unaffected, and simply lashed Ice Man with a tendril, splitting him in half, and consuming him. Mercer's fingers briefly froze as he gained a new power, but he did not use it. Magneto was occupied, fighting against a group of monsters that had been specifically built to have no metal in them.

Mercer reached Xavier, picking him out of the wheelchair and glaring at him. Storm fired lightning at Mercer, but it arced all through his body, having no effect. Spider Man saw the danger, and saw a way he could stop Mercer. Peter jumped over to the now regenerated Wolverine. "Logan. I need your help. You attack him and I'll get that helmet off him."

Wolverine jumped at Mercer, but was struck to the side in an instant. Spider Man fired a web line onto the helmet, but Mercer expanded his head, stopping the helmet from coming off. With a toss of his head, Mercer dragged Spider Man down to the floor. Mercer lashed at Spider Man with a tendril, but Peter jumped over the attack, jumping onto Mercer's head, attempting to remove the helmet. Mercer released an explosion of tendrils, tearing up the entire mansion. Spider Man dodged the tendrils, escaping unharmed, and Xavier protected himself with his psychic ability, but others were less fortunate. Cyclops took a tendril through the chest, and was consumed. Nightcrawler dodged the tendrils by teleporting, but was still injured due to slower reactions than Spider Man and Charles. Storm and Magneto were able to protect themselves, but Mystique was also consumed.

Magneto used his magnetism to lift Mercer into the air, attempting to crush him so completely as to destroy him. As Magneto seemed to have defeated Mercer, Mercer's eyes turned red, and a laser beam flew from them, hitting Magneto. Before Magneto could recover, Mercer swiped him through with a tendril, consuming him. Mercer then jumped onto Phoenix, who threw him aside with her telekinetic power. As he was flying aside, his tendrils flew in all directions, tearing up and consuming Storm, Colossus, Nightcrawler, and most of his creatures.

Spider Man suddenly had an idea. He dropped onto one of the creatures, punching it out. Mercer attacked Peter, but Phoenix again tossed Mercer away. Lacking a syringe, Peter picked up a pen from a nearby desk, stabbing it into the creature. Peter then stabbed the pen into his own arm, infecting himself with the Mercer virus. Peter cried out, falling over. Mercer reached down to pick Peter up, but Peter struck Mercer's hand aside, kicking the other infected to the other end of the room.

Peter then jumped onto a monster with claws, tearing it apart and consuming it. In an instant, Peter gained claws. He then shredded a monster with tendrils, before consuming a monster with blades and shields. After consuming the last of Mercer's monsters, Peter felt like a monster himself. A powerful monster.

Mercer dived at Peter, but Peter struck him back with a hammer fist. Mercer lashed at Peter with tendrils, while Peter, who still possessed his Spider Sense, was able to dodge every attack. Finally, Peter attached web lines that were also tendrils to Mercer's arms, tearing them off and consuming them. Peter felt his strength grow as he gained what he knew was the Hulk's unlimited strength. Peter then continued to strike Mercer, with Mercer recovering, growing his arms back and using blades against Peter.

Peter dodged most of Mercer's attacks, before wrapping webs around Mercer's head, ripping a part of it off and consuming it. Mercer regrew his nose and chin, but Peter still gained what he recognised as Cyclops' optic blasts. Peter and Mercer blasted each other with the optic blasts, before Peter dived over Mercer, slamming a blade through him, consuming a portion of him. Peter gained in that instant the powers of everyone Mercer had consumed, now being as powerful as Mercer himself. Peter then gripped Mercer, and Phoenix used her telekinesis to lift both of them into the air. Taking advantage of Mercer's weakened state, Phoenix lifted Juggernaut's helmet off Mercer, and instantly, Charles' mind control was effective again, and Mercer froze, struggling to attack. Peter stepped back. "We don't need to kill him."
Somehow fighting Xavier's mind control, Mercer's eyes turned a darker shade of yellow, and his body erupted in tendrils, which threatened to kill everyone in the mansion. Peter gripped Mercer, releasing tendrils of his own to restrain Mercer's.

Mercer smirked, struggling to break free of Peter's hold, which was the only thing stopping Mercer's tendrils from consuming everyone in the mansion. Realising he had no choice, Peter slammed his fist through Mercer, changing his fist into a hammer, then a blade. With a grunt of determination, Peter ripped Mercer's torso apart, consuming Mercer and his tendril attack.

Peter felt the full extent of the Mercer virus fill him, and he collapsed onto his back, groaning.

A few weeks later, Peter was sitting in the medical centre of the rebuilt SHIELD helicarrier. He had been starting to feel Mercer's emotions, and that bothered him. He had heard from Xavier that it was possible to remove the virus from him, as unlike Mercer, Peter had kept his original body, and could simply remove the virus from himself. This required the help of a man named James Heller.

James Heller entered the medical centre, nodding to Charles and Thor. He sat down next to Peter.
"I hear you ate Mercer. Good riddance. Been meaning to do the same myself."
Heller put a tendril into Peter's arm, draining the virus from Peter's blood. The process exhausted Peter, and he passed out.

Peter stood on the edge of the carrier the next day, thanking Heller for what he had done.
Heller shrugged. "Don't worry about it, kid. You did me a favour by killin' his ass for me."