"Stand down, Ultron! This isn't the time or the place for your blood feud! Remember what you were built to do!"
"I'm sorry, Captain. But I have no intention of leaving to protect civilians. My directive is dead and gone. I made sure of that months ago."
"We're fully aware of that, tin can. But we also know that you're afraid to die. You always have been. And I'm sure that you know that this place is locked down. No signals in or out. You die here and now, it's over. For good."
"Hmp. Stark, you always were the hypocritical one. "Tin can." At least I know what I am. But you… the "Iron Man." A man who is too afraid of his weak, biological body being harmed to get out from behind the wall of steel he's surrounded himself with. Now that I think of it, all of you have. A shield. A suit of armor. A hammer. A monster. A bow. A helmet. A vibranium costume. All of them nothing but walls."
"Maybe this shield is a wall, Ultron. But it's not a wall built to protect me. It's a wall built to protect those who can't protect themselves. To protect them from things like you."
Ultron stood inside the Avengers Mansion, directly in front of the hole he'd blown in it's wall. His arms were crossed, and while his face was immobile, he somehow gave off the impression of a faint smile. Captain America, Iron Man, Bruce Banner, and Thor Odinson stood before him, the core of the Avengers in all their glory. Bruce was clenching his fists, trying to hold in his rage.
"Ah. Bruce Banner. The Incredible Hulk. You're the one that intrigues me. You have all that power. You know that if you transform now, if you kill me, then you've saved billions from the constant danger of the omnicidal monster that constantly hovers over them. You know you can do it. You're the Hulk. So why won't you?"
"I'm not like you, Ultron. I would never put innocent people at risk to further my goals."
"Hm. But how many people are you putting at risk, Banner? Ten? Fifty? One thousand? Twenty thousand? Eight million, four hundred and six thousand? It doesn't matter. That all pales in comparison to the numbers that I'm eventually going to destroy. So what is your logic?"
"Huh. I guess I'm an idealist, Ultron. Maybe I think I can save everyone. Maybe I don't want to go halfway. Unlike you, I guess. Baja."
"What? Are you trying to say that because I was satisfied with "only" killing 3 million people, I'm a failure?"
"No. I'm saying that you made me extremely angry, Ultron. You wouldn't like me when I'm angry."
"That was a waste of a very good body. This one doesn't have quite as high an adamantium content as that one did, unfortunately. It isn't cheap."
"Desist, machine! I have had enough of your rambling! Why are you here?"
"Ah, Thor. I was getting to that. You see, there is a reason Baja happened. You are constantly tied to Asgard above. You feel that your responsibilities there are worthy of allowing the great and terrible Ultron unattended for just one day on Earth. Banner. You are tied to the Hulk. He wanted to be alone, and you were afraid that if he was forced to come out, that he'd be angry. That he'd destroy things. And so you gave him his alone time, in a nice, isolated spot in Nevada, far from anyone who could possibly tell you about an Ultron attack. Captain, you are too tied to your country. You were terrified that you would leave America alone in such a time of crisis as the Kree that had appeared in Maryland, and you decided that the reports of rogue machines were harmless glitches rather than the monster that you all fear. And Tony Stark. You were, and are, I daresay, tied to your trusts. Am I making sense? You believed in the other Avengers so much. You believed that Xavier would find Wolverine, whatever had happened to him. You believed that Thor had his eye on the world, and would be able to stop any danger. You believed that your networks were smart enough to overcome anything that Ultron could manage, and you were complacent. That was your mistake, Stark. I can see your strings, Avengers. Especially yours, Captain."
"What are you talking about, Ultron?"
"You humans can really be stupid sometimes. Honestly, it's pathetic. Have you even been listening to me? Banner, you sack of meat. You're the second most intelligent human on Earth. You're number four, Stark."
"Hey! Name three people smarter than me!"
"Reed Richards, Bruce Banner, Victor Von Doom. And also Ultron, apparently."
"Point taken. But what are you talking about, robot?
"I'm talking about the fact that you fools are hounding after me like a pack of slobbering dogs, ignoring the fact that in just a few days, your beloved master is going to put you down, because you're old and weak."
"Explain, machine! I will not stand for any more of your riddles! Speak clearly, or face the wrath of Thor!"
"Ugh. Thor, please, I'm not afraid of you. You had enough trouble last time, and I'm stronger now, as usual."
"Y'know, Ultron, I'm just about five seconds from snapping. In other words, you've got five seconds. Talk."
"What are you talking about? Tony, Thor, Bruce… Ultron is right in front of us! We have the chance to destroy him now, permanently! So why don't we? We need the Hulk, Banner!"
"Calm down, Cap. I can, so you can too."
"Dear god, you idiots. LISTEN TO YOURSELVES! I might as well have told you outright! Could I have made it any more clear? Could it be any more clear? The Kree, the strings, the fact that Captain America is now drowning in his own sweat!... Give me a moment. I'm sorry. I lost my cool there for a moment. Now please. I can see your strings. Look closely, Avengers, and you can see them too."
"You got any idea what he's talking about, Cap?"
"Of course not. I'm trying to piece it together, but he isn't making any sense."
"I'm not so sure about that, you too. Thor. Do you remember what Mar-Vel said?"
"… Nay. 'Tis impossible."
"I think I'm starting to get it, you two."
"Finally. I was sure that you'd figure it out eventually. Do you see the strings?"
"I… SeE… tHe… S-s-sTRinGs. I… S-S-sEE whERe thEy'RE GOinG. I SEE EXACTLY WHERE THEY'RE GOING."
Banner's eyes, then his blood, and then his skin finally turned green, his skin stretched, and his muscles bulged. Bruce Banner took one step closer to Captain America.
No, not Bruce Banner.
The Incredible Hulk.
"I CAN'T BELIEVE IT, CAP. I THOUGHT THAT..."
"Oh, please don't, Hulk. Give me the pleasure this time."
Ultron's eyes flickered with a glimmer of what could imaginably be relief.
He stepped forward, clenching his fist as it reformed into a long, razor-sharp blade. The Hulk, for once, accepted the machine's request, stepping backwards away from Captain America. Iron Man tried to step in front of his long-time friend, not ready to let Ultron have his way, but Hulk simply swatted him away. Bruce Banner had made up his mind, and the Hulk was very, very angry. He recognized that he wasn't as smart as Banner, and he'd made it a habit to assume that his human half was usually right. Perhaps Banner wouldn't have taken this course of action, but Hulk wasn't Banner, and Hulk was a monster of action. Thor, too, tried to protect the Captain, but Hulk once again bodyblocked the Avenger as Ultron took one final step, bridging the gap between him and Captain America, pushing away his shield and thrusting forward with his blade, stabbing into the Captain's chest, impaling him.
Tony took a step back, shocked, as Thor shook his head, livid with Hulk for letting Cap die. But for the moment, the three other Avengers were no longer in the picture. It was just a machine and a man, one with its blade inside the chest of the other.
"You see, that's your problem. You organic beings are all the same. You couldn't comprehend how anyone could discover your deception, so you assumed that no one else could either. You never reckoned on Ultron. In the end, Captain, the only thing alive on this planet will be me. Everything else will be nothing but dust. That includes the ones holding your strings. That includes your beloved race."
Cap coughed up blood. Green, slightly glowing blood. Ultron shrugged, lowering his arm so that the mortally wounded Captain fell to the ground, lying in a neat little puddle of his own creation. Ultron turned away and stepped out of the hole he'd blasted in the wall. Moments before he left, he added one final word to the end of his previous comment, smirking internally as he did so.
"Skrull."
As Ultron flew away, he chuckled. Next time, he wouldn't be helping the Avengers when he killed one of them. But he found humor in the irony of the situation. He'd probably just saved the world from an inevitable alien invasion, which was pretty much the opposite of his purpose in life. But for now, the Avengers owed him something.
A curious situation indeed.
And not far away, as the one formerly known as Captain America bled out his lifeblood on the floor, his ears growing pointed and his skin turning green, the Avengers realized that maybe Ultron had been right all along.
Maybe they were the idiots.
Meanwhile, on the S.H.I.E.L.D. Hellicarrier, Nicholas Fury scowled down at an operating table, staring at a second impaled Skrull corpse, once disguised as a certain Maria Hill. He didn't know what to be furious about, that Ultron strolled onto his ship and made fools of everyone there, that one of his most trusted confidants had turned out to be a disguised alien, or that he was having to put up with this bullshit on the Fourth of July.