Not too long after rounding up the villains cohorts of Lex Luthor after the disappearance of him and Darkseid, the Justice League returns to the Watch Tower to stand watch over the world. With their old friend and founder J'onn J'onzz found, he returns to the League and helps with their newly set task. The Justice League founders sat around their meeting table to discuss the new task at hand.

Superman: So you see, I've realized that despite our League's current significant size, we need to keep recruiting.

Wonder Woman: What exactly would this endeavor entail Clark?

Superman: We need to search for younger people with superpowers, children if you will.

Green Lantern: Are you sure that's a good idea Superman? I mean, a child superpowers isn't likely able to control their powers well and I don't know how much of them are actually around.

Superman: No matter how few they are, we need to find a recruit them. We'll be able to either train them to control their abilities, or they'll know how from any previous villain-fighting experiences.

Batman: Clark, even if we could find child-heroes, what would the purpose of recruiting them truly be?

Superman: Well Bruce, you know that we and the League's current members won't be around forever and the world may still need heroes in its future.

Flash: Oh, I get it. If we recruit younger heroes today, they'll become the Justice League of tomorrow once they're grown up.

Superman: Exactly, Flash, the J'onn is already undertaking the task of searching Earth through news broadcasts and his psychic powers to find super-powered children.

Suddenly, Superman gets a telepathic message from J'onn, as did the rest of the League and they go into the computer room.

Wonder Woman: You called us J'onn, have you found any young heroes to recruit?

J'onn J'onzz: I have, 2 to be exact. A boy and a girl, cousins, named Ben and Gwen Tennyson. Ben has a powerful alien device upon his wrist, with which he can transform into any alien being depending on the DNA within the device.

Superman: Any impressive quality. And the girl?

J'onn J'onzz: She poses a great talent with sorcery, far different from the magics we've encountered in the past. Also, I have seen their past achievements through Earth media and when I mentally sought out their minds. It is in my opinion that they would be fine assets to the Justice League, present and future.

Flash: Well what are we waiting for? Let's bring them up here.

Meanwhile, Ben, Gwen, and their grandpa, Max Tennyson, are on the road over the last few days of summer. Things had been quiet for them of late and Ben was getting bored.

Ben 10: Man, where did all the criminals and bad guys go?

Gwen: What kind of question is that? I'm rather enjoying a break from all the world-threatening crises.

Ben 10: That's because you have other ways to occupy yourself other than fight them, I don't really have any.

Max: Now Ben, complaining like that isn't going to make something happen to resolve your dilemma.

Suddenly, a light starts flashing on the rust bucket's dashboard.

Gwen: What's that Grandpa?

Max: It's an anomaly detector I recently installed.

Ben 10: Finally, something good coming our way.

Max: Now Ben, let's not get ahead of ourselves, I have to find out what it is first.

Suddenly, in a flash, Ben, Gwen, and Max disappeared from the rust bucket and it ground to a halt on the said of the road.

The next thing the Tennysons knew, they were on a huge space station, orbiting the Earth.

Gwen: Where are we?

Ben looked around to see the Justice League all around them and burst with excitement.

Ben 10: We are on the Justice League's Watch Tower. The Justice League is a group made up of the world's greatest superheroes, fighting to spread protection and justice all over the world.

Max: Thanks for the heads-up, Ben, but that doesn't explain why we're here all of a sudden.

Superman (flying down to them): I can explain that, Mr. Tennyson. We've learned about your grandson and granddaughter's exploits during your summer road trips, very impressive.

Ben 10 (whispering to Gwen): You hear that, he knows about our achievements as heroes.

Superman: Sorry about the surprise, but we need to talk to them.

Gwen: Sure Superman, what is it you need?

Superman: Gwen, Ben, as you know, the Justice League won't last forever, age still catches up to heroes and they need successors. So I've been undergoing a task to recruit super-powered children into the League to eventually take our places, while still helping us to protect Earth today.

Ben 10 (joyful): You mean you want us to be the 2 newest members of the Justice League!?

Superman: That's right, Ben. We've seen how capable you and your cousin are in dealing with great dangers and villains.

Gwen: Superman, I don't know what to say. Being recruited into the Justice League would be quite an honor.

Max: Just one thing, Superman. Their parents are going to have to know about this and despite their 'achievements', they're still kids that need protection.

Superman: I assure you, Max, their families will know where their kids are now and we will protect them as we do with all our fellow Leaguers.

Max is teleported back to Earth, while the League's 7 founders give Ben and Gwen a tour of the Watch Tower.

Ben and Gwen are set up with their own room in the Watch Tower.

Ben 10: How cool is this Gwen? Us, the Justice League's 2 first 'junior' heroes for the League's future.

Gwen: I have to admit I agree with you for once, Ben. It's real cool.

Ben 10: Our days of boredom are over, the Justice League fights evil aliens and supervillains all the time. And I just thought of something, if the Omnitrix can collect the DNA of whatever 'alien' touches it, maybe it can do the same with super-powered humans.

Gwen: Wait Ben, are you saying that if you can get every member's DNA, that you could turn into any of them with any of their powers?

Ben 10: Oh, it's like you read my mind, Gwen, that's just what I had in mind. And I'm sure the League won't mind, it's for the League's future, even if they age into retirement, they can continue hero work through my watch, and they'll never be forgotten as heroes either.

Gwen: I guess that's true, and in any of those hard times, you could use the Omnitrix to pose as a decoy to distract them from any specific Leaguer.

Suddenly, a large red light blurs through the Watch Tower with a loud siren noise.

Ben 10: And it keeps getting better; we're going out with them on the first day.

Ben and Gwen get right up and meet with the rest of the Justice League for a briefing. An image appears on a big computer screen, showing an invasion from space, the ships were easy for Gwen and Ben to recognize.

Ben 10: Vilgax. Man, that squid-faced creep never gives up.

Batman: You know that alien?

Gwen: Unfortunately, yes. He's Ben greatest enemy, always trying to ravage the Earth.

Ben 10: He's also always after the Omnitrix, my alien transforming device. But each time he's come around, we've beaten him. And now with all of you there with us, it's sure to go 10 times as fast.

Gwen: I suggest we give him a little welcoming committee on Earth. We'll send a message to him, me and Ben since we know him, and pretend to discuss terms of surrender, and he'll find all of us waiting for him.

Green Lantern: Hey, that's a great plan young lady.

Ben and Gwen sends their 'surrender' message to Vilgax, but he grows suspicious of it.

Vilgax: It must be a trick, Tennyson is obviously up to something. But he shall be surprised when he finds the army I've made just for this reunion.

Vilgax turns around and presses a button, revealing an army of brainwashed aliens recruited from across space, all similar to the ones on the Omnitrix.

Vilgax: What this army, Tennyson shall be powerless to stop me. With not just one, but every locatable alien similar to those of the Omnitrix at my fingertips, Tennyson's powers will be eventually matched on all fronts.

Vilgax descends to the location on Earth indicated in his message, where Ben, Gwen, and the Justice League are waiting for him.

Vilgax exits his ship to find Ben, Gwen, and the Justice League all there.

Ben 10 (turning into WildVine): Welcome back, 'Villy', get ready to repeat history and get your butt kicked back to the other side of the universe.

Vilgax (revealing his army): It seems you've made new friends since our last encounter, Tennyson, but so have I.

Ben, Gwen, and the Justice League stare in surprise at the hoard of aliens Vilgax has.

Vilgax: And with them, this planet shall be mine to rule.

Ben 10 (as WildVine): So you got some extra muscle, huh? No problem, nothing the Justice League can't handle.

But Ben's proven to be in over his head when he gets overpowered each time he tries to fight the aliens with his own heroes. Gwen's magic proves effective and the rest of the League hold there own against Vilgax's army. However, none of them find the 'Achilles' Heel' for Vilgax, Ben was the only one who truly knew how to defeat him, but couldn't with multiple aliens similar to his own on Vilgax's side. Then, he got an idea and huddled Gwen and the League together.

Ben 10: Look guys, fighting aliens similar to those on the Omnitrix is difficult for me, but I have a plan.

Flash: Well let's hear it.

Ben 10: The Omnitrix has the ability to absorb the DNA of any alien that touches it, but I think it could do the same with super-powered humans like all of you.

Green Lantern: You mean with that thing, you'd be able to get our powers?

Gwen: That's exactly what he means. And with them, he'll have new tactics against Vilgax, he could even pose as a decoy and lure the aliens away from each of you at different times.

Wonder Woman: That's a grand plan, but how do we place our DNA inside the device.

Ben 10: Just touch the edges near the light circle, when it glows 'yellow', it will have gotten your DNA.

Each Leaguer touches the Omnitrix to implant their DNA inside, once the League's 7 founders (exluding Batman who has no powers) have gone, Ben turns into a duplicate Superman and charges through the aliens. By the time he changes back, he's inside Vilgax's ship and searches for a way to free the alien army from his control, but Vilgax follows him inside.

Vilgax: So, your friends have given you some knew talents with the Omnitrix, I see.

Ben 10 (Turning into Flash): You got that right. In the blink of an eye, I can now be any of the League.

After an abrupt 'Justice League' fight with Vilgax, Ben finds the computer and uses Grey Matter to free the aliens from his control. Afterwords, the League and aliens force Vilgax off the Earth and back into space.

Later, back on the Watch Tower, Ben and Gwen are both commended for their efforts and achievements on their first day in the Justice League.

Superman: Ben, thanks to you, the planet is safe again.

Ben 10: Hey, I couldn't have done it without all of you, and not just your DNA, because we're a team.

Wonder Woman: I can already tell you, Ben, you and Gwen are well on your way to becoming great members of the Justice League. And through your device and our DNA, our ideals, powers, and our legacies will live on even without us.

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