Trigger is a happy kid with a VERY uncommon life. Shortly after his birth, he was placed in a secret underground training facility in order to be turned into the ultimate sabotage machine. You see, his home planet was scheduled to undergo a dangerous, experimental terraforming procedure to turn it from an icy rock to a warm, temperate paradise. As it happens, certain parties felt it was TOO dangerous to be attempted, and felt the best response was raising a baby to tear up the terraforming machinery. BUT, thanks to some bureaucratic silliness, the terraforming ended up taking place before Trigger's training had been completed, and lo and behold, the planet wasn't destroyed. Immediately, the super-secret revolutionary environmentalists fled in embarrassment, not even bothering to shut their plan off. Thus, Trigger was forgotten and left in the underground bunker, with only Layla and her Dad to take care of him. That is, until Ichabod discovered him and offered him a chance to see the universe.
Most people in Trigger's situation would be understandably grouchy. After all, his entire short life has been wasted on a botched plan and he knows next to nothing about the rest of the universe. Trigger isn't most people, though, he's a pure, cute, innocent, wide-eyed little kid who loves smile and hugs. Trigger is EXHAUSTINGLY happy, and he wants nothing more than to see everyone else happy too. He adores Layla as his best friend/big sister/almost kinda Mom figure, but there's not a person alive that Trigger doesn't like. He's just that kind of kid. Also, he can dismantle starship reactors in his sleep, which comes in more handy than you'd think.
It's also worth noting that trigger loves to run around in loose-fitting hippy fashions. Not so much because he's any kind of hippy himself (though it's not hard to picture him frolicking naked in a field), it's all thanks to puppy luv. Trigger has a MASSIVE crush on Skye, a young professional saboteur who travels around with a band of Jesus Freaks. Thus, anything she thinks is cool (like second hand flower child ponchos) HE thinks is cool. It's awkward and embarrassing but just so gosh darn adorable.
Q: We know you said not to ask about specific character age, but seriously, how old is Trigger supposed to be. You say he's younger than Layla, but they're the exact same height. And yet, the kid acts like… well, a KID! How old IS he?
A: He's as old as he has to be for the specific page you're reading to work. That's all.
…naw, I'm not gonna leave it at that. Don't worry. Trigger's somewhere in the twelve/thirteen range; old enough to have discovered girls, but not old enough to know what to do with that information. The reason he and Layla are the same height is, well, 'cos it took me a while to figure out they weren't actually the same age. The emergency in-universe explanation is that Trigger's always been kind of tall for his age, and Layla's kind of NOT tall. As for the wide-eyed innocence… that's just how Trigger is.
Q: How was this “child super saboteur” plan even supposed to work? Why not just pay someone who was ALREADY trained at sabotage to do it?
A: Because then they'd have to keep hiring new people over and over every time the terraforming stuff was repaired. Trigger would always be ready and willing to take out his target, again and again and again, because he literally wouldn't know any better. Of course, that's assuming Trigger would grow up with no influences other than his training machinery, which didn't end up happening. And it also assumes that there'd be time to DO all the training, which obviously didn't happen either. No one ever said this was a good plan.
Q: Technical skills aside, Trigger doesn't seem very cut out for the job of a super saboteur. He can't lie to save his life and doesn't seem to like making people unhappy. How was this kid supposed to do his job?
A: Again, nobody said this was a good plan (Then again, soft-heartedness aside, Trigger DOES seem to enjoy a goodnatured prank every so often, so at least a BIT of that training suck in)
Q: Trigger and Layla seem to get along really well. Like, really REALLY well. Is there anything more going on there?
A: Nope. Sorry shippers, but Trigger and Layla will never EVER be an item. Yes, they obviously love each other, but it's totally, one hundred percent “like a brother/sister” territory. Besides, he’s clearly got a crush on somebody else already! Our Trigger's no two-timer!
Q: What about him and Jenna? Is that ever going to happen?
A: Sorry shippers, but no. Aside from the fact that Trigger's hung up on Skye, Jenna's moved on. I mean, let’s face it, she is WAAAAY more mature than he is. And there's still the whole “played manipulative mind games on her little brother” thing. Well-meaning or not, that’s a bit of a turn-off for Jenna.
Q: We get that Trigger’s all naive and unfamiliar with the worlds, but HOW naïve is he supposed to be? Sometimes he doesn't seem to know anything about anything all, other times he seems as normal as anybody else. How much does he actually know?
A: That's another “whatever it takes to be funny” question, right there. Trigger is as uninformed as he needs to be for a given joke to work. In universe, he's not TOTALLY oblivious to the rest of human society, just mostly so. This training simulators told him everything they figured he'd need to know to pass as “normal” in a crowd, though, as we’ve seen already, that stuff wasn't exactly a flawless plan. Also, Layla and her Dad brought a lot of kid's books and movies down for him, which gave him a further taste of the worlds above. That was wildly against the rules, of course, but since when do career criminals care about rules? But still, that's so substitute for actually LIVING in the outside worlds, so he’s knowledge of things is very incomplete.