There's a long list of names the JLU is fond of calling Kai-ro: Green Lantern, prodigy, genius, hero, shrimp, kid.
Kid. He hasn't been a kid in a long time. Sometimes he's not even sure he ever was one. Raised by monks, then the Corps, Kai doesn't think that counts as a normal childhood. It's not like he hasn't tried to experience childhood before, but nothing ever works. He may be a prodigy, but this is something he can't make himself understand. Sometimes he watches the second-youngest Leaguer, Batman Terry McGinnis, and wonders how he manages to maintain two lives. Kai only still uses his given name to avoid confusion among the other Lanterns. He doesn't have a secret identity to hide. He doesn't have to go to school—some Leaguers are teachers and have been tutoring him for years. He doesn't have a younger brother, a girlfriend, or friends to keep from harm. Terry ironically remarked that Kai was lucky on some of these parts. But all of it is why Kai envies Terry.
"Keep it together, Lantern," Batman warns, cutting off his train of thought. Kai takes a breath to remember where he is: in a dark, underground disaster area with thirty kids and no motherbox. A field trip for a Gotham elementary school went horribly wrong, and now he and Batman are trying to get these kids out of here in one piece. The problem is that only one of the kids isn't afraid of Batman—a third grader named Matt—and the rest are starting to panic. Because Kai is about the same age as them, it falls to him to lead them out of danger while Terry keeps an eye out for any threats. Kai has a shield around them just in case, casting enough light so that they can see the path ahead of them. The entire city's out of power, it seems, and it isn't helping Kai's nerves. The sooner they find the rest of the League, the better.
Someone starts sniffling, and Kai turns his head. The youngest in the group, a kindergarten-age girl, is crying. Kai gives Terry a pleading look, but Batman only brings her up to Green Lantern before heading to the back of the line again. Kai somehow finds the voice to say, "It'll be all right. We'll get out of here," and the girl looks up at him. He offers a smile, and she nods, holding his hand. And now, he starts to think that maybe they will make it out of here.
"Are you picking up anything now, Batman?" Kai asks again. He's forgotten how many times he's asked this.
"Signal's weak, but it's coming in," he answers for the first time. "I think we're underneath a part of the city that still has communications. I should be able to contact Superman in a few feet."
"We don't have a few feet," Kai warns. Their road on the old subway system ends at the even older sewers. A rushing current of water from the storm above is making it impossible to wade through. He insanely wishes there was some kind of creature in it, like an alligator in urban legends, just so it could carry a message to or from Aquagirl and they could get out. But instead, he focuses a second beam from his ring into a high bridge extending as far as he needs. The bubble stays up around them to protect them from the current as he leads them on the emerald bridge. The small girl next to him tightens her grip on his hand, and he knows how scared they all are.
"This is strong enough to hold us all, right?" Terry asks, voicing their concerns. Even though he's twice as old as the oldest kids, he's still more in-tune with them—maybe because he was a kid once, unlike Kai.
"It'll hold," Kai replies.
The farther they walk, the longer he extends the bridge. Their "few feet" turns into half a mile, and the kids are getting tired and even more afraid. Terry signs to Kai that he lost the signal again and probably won't be able to get it back. Kai nods and starts looking for a dry spot to land. They've wandered far enough to find what might once have been a villain's stronghold—which explains the lack of communications. Kai leads them in and all but seals up the hole in the wall, keeping the water out.
"We'll rest here for now," he tells them, and they gratefully sit down.
"I'm cold," someone complains, and Kai uses his ring to scan around for anything they can burn. He finds some broken, rotted old crates and brings them over.
"Stand back," he warns the kids as Terry takes out a signal flare and ignites the wood. With a fire blazing, everyone concentrates on warming up and drying off.
"How long 'til we're out of here?" the third grader, Matt, asks. Kai notices that he's the only one sitting anywhere near Terry. The other kids try and keep as far away as possible out of fear.
"I don't know," Terry confesses. "From the look of it, I think we're in Killer Croc's old lair, so we're pretty far from where we fell."
"How deep are we?" Kai asks, looking up at the ceiling.
"Deep enough, but I think you might be able to get a signal out with your ring."
Kai gets up and scans the ceiling for its weakest point. He lets the shield around the wall drop so he can concentrate on putting one up on the ceiling around where he's going to focus a beam. It takes a while to dig through the rock, and he has to navigate around power lines, but he manages to create a tunnel to the streets above. Once he's certain that the ceiling won't collapse on them, he fires a pulsing beam into the narrow tunnel.
"Try and get some sleep," he advises. "This could take a while."
After a while, he forgets how long he's been doing this. His arm aches, but he ignores it as best as he can. He tries to meditate, but he can't force calm into his mind. Thirty children are counting on him to get them to safety. He looks around at them and notices how calm they seem to be in their sleep, even despite their circumstances. He can't remember a time when he ever slept like that; all of his life, he's had to keep partially alert in case of danger. The closest he gets to that is the inner peace he finds in meditation.
"I'm watching them," Terry offers. "They'll be okay."
"If we can get out of here," Kai reminds him.
Terry frowns. "Not very optimistic, are you?"
"I guess not," Kai answers. "How are they?"
Terry stands up and walks over, and Kai is suddenly aware of how much taller his new teammate is. Kai's height is far from impressive; the medics back at the Metro Tower predict that his growth will always be stunted because of having so much ring radiation in him at such a young age—yet another thing an ordinary child wouldn't have to deal with. An ordinary child also wouldn't be so realistic, knowing that at eight years old, he stands a very good chance of dying in combat. A boy's life on the battlefield changes his perspective on things.
"I think they'll be okay," Terry affirms. "They're wet and cold, not to mention bruised from the fall, so they'll need some medics to look at them before their parents come. But all in all, I think they're going to be fine."
"You think?" Kai repeats.
"There's always the possibility something could go wrong," Terry confesses, in a rare moment of solemnity. "That lightning strike that collapsed the building we were in is going to be causing trouble for everyone above. They might think we're still down there if we're still alive, and they might not think to look here. And if your ring falters, that might also happen."
"It won't," Kai promises.
"I read up on the Green Lanterns when I joined," Terry explains. "I know that the ring is governed by their hearts and minds, and I know you've been worried…"
"I won't fail you," Kai assures. He won't mention that his ring will be out of power in an hour, thanks to all he constructs he's had to do. There's no need to worry him. Terry believes him and returns to watching the kids.
Knowing that he needs to conserve energy, Kai switches from a pulsing beam to flares. Each one explodes over Gotham like a brilliant green firework. He tries not to do too many at once, waiting five minutes before throwing up the next one. He knows it provides a less precise location, but he has faith that they'll find them.
He probably has fifteen minutes worth of power left when a blinding white light appears in the room. The kids moan as they wake up to paramedics coming through the boom tube, getting them on stretchers. Kai and Terry grin at each other in relief as they help get the children through the boom tube up to the surface. Superman, Micron, Barda, Warhawk, and Aquagirl are standing there along with three ambulances and dozens of parents, who rush to their children. The League is far more reserved about it, though Aquagirl grabs them both in a hug. From the embrace, Kai manages to peek to the side to see the reunited families, and he thinks that maybe he's all right with giving up his childhood if he can let other kids enjoy theirs.
I don't own Batman Beyond or Justice League Unlimited or any of the characters involved. This was partially inspired by the Kakashi Gaiden chapters of the Naruto manga—how the battlefield affects a young child. Kai always seemed pretty serious in canon during his appearances, so I figured he probably doesn't have much of a childhood because of being a superhero at such a young age.