There are two things I thought of recently, regarding Artemis Fowl. Sort of. They are kind of the same thing, but anyways.
1) When Arty kidnaps Holly Short, and then lets her go, that all takes place in the span of about 36 hours. She is kidnapped one night, kept the next day, that night the LEP tries the time stop, and then she is released in the morning. So lets call that 36 hours, and when she is released, it is Christmas Day, December 25th.
Now, we know Artemis did all this when he was just 12 years old. We also know there were months of planning and trying to find a fairy, and then 4 months of stakeout before Holly was caught.
Artemis Fowl was born September 1st. He started this search when he was 11 years old. Then he turns 12 and finally gets a chance to by finding the sprite and doing stakeout.
This was a literal child who just wanted his father back, and his mother back, and would do whatever he had to to do that. Which leads to point 2:
2) A lot of people in the Fowldom are always like “Why THE FUCK is Butler letting A CHILD run around and kidnap fairies? He is a terrible father figure!”
But I mean, lets face it. Butler has seen some shit. He’s seen terrible things happen to people physically, and emotionally. He is aware of the trauma and mental scarring Artemis has gone through after hearing that his father’s ship blow up and watching his mother descend into insanity. Butler is also paid to protect Artemis, not question his decisions.
Then you add in the fact that Butler doesn’t for one second believe in fairies until he sees them. Basically, as far as I can tell, Butler is letting a child run around chasing fairies because what else is he gonna do? Leave? Leave not only his families centuries-old position, but leave a small boy with no family? And since Butler is fairly convinced fairies don’t exist, what’s the harm in looking? Yeah, traveling the world and meeting shady characters makes his job a lot harder than it needs to be, but if that’s how Artemis – a genius child that Butler probably only slightly understands how his mind works – copes with the (probable) death of his father and loss of his mother, then who is Butler to argue with that coping mechanism?
At least Butler has done all he can to keep Artemis safe during those travels, and made them as easy as possible for the boy. And even when fairies are real, and there is one in the manor, Butler does his best to keep Artemis safe and convince him that kidnapping human-like sentient species is Not A Good Thing to Do. He tries to teach Artemis morals to the best of his ability, while keeping him safe physically, and quite possibly mentally by being supportive for all of Artemis’s schemes.
So yeah. Arty was a literal baby when he kidnapped Holly, he only had proof of his idea like, a week after he turned 12 (12! He’s not even a pre-pubescent teenager! He is just a pre-teen! A lonely little preteen boy with no friends and no family who just wants his father and mother back!) and Butler was as supportive as possible (and arguably very father-like because of it) to a damaged boy who had essentially lost everything except that support.