His number one rule was No One Gets Hurt. Fair play, mimimalizing property damage, and returning the stolen goods (provided they weren't the Pandora Gem, although since that one has yet to be found the point was rather moot) also ranked high on his list of priorities. He gave advanced (if cryptic) warning for his heists, and tried to minimalize injuries to a few (heavily) bruised egos. Some might even call him honourable, if not moral.
Kaito wanted to laugh at the irony.
Sometimes he wondered if it wouldn't be better for him to just let it all go. No doubt he wanted to take down those black-hearted bastards, but did that come secondary to the revenge for his father or did vengeance go in second place? It was hard to tell, sometimes--old wounds fester in the heart, and those two had been chasing each other long enough that it was near impossible to give either up.
So he continued, because he could...and because he didn't know how to stop. And because the Law, as much as it tried, often failed to keep up with Justice. In all the myriad of paperwork the cops tripped themselves over to keep everything politically correct and their asses covered, the crooks have already long gone, leaving the righteous and justified far behind, coughing in the dust of their wake. Maybe that's why his father took up the monocle, to cut through the bullshit red tape. Highly illegal, of course. But effective.
(Or was it? Did his father have that altruistic an intent behind his stealing, at least at first? Like his son, his father's original motiviations were so mired in primaries and secondaries and aged with time it was impossible to sort through them all, and it wouldn't do to chase ghosts of the past for a man long dead. Even if Kaito was living it now, himself, and he was--hopefully--still a long way from dead.)
But he was doing it for a good cause, right, regardless of his original intentions? That's how he justified it to himself.
The ends justify the means.
Or did it?
He tries to keep it straight, keep it clean as best as he could--maybe to try and console his aching conscience, or to prove a point. He aced school without effort, knowing far more than even his teachers although he never lets on. He breezes by exams without studying...but he has to, because so much of his other life depended on the practical application of such knowledge. Some things he couldn't ask ("Sensei, how do you make a flash bomb?").
He tries to make all his gadgets and dangerous tools himself, improvising when his father's notes and Jii's experience couldn't cover it. Aoko's never found out why he had so many scars on his arms and legs--daring escapades and chemical burns both. He almost blinded himself, once, synthesizing nitroglycerin. He wasn't sure if it was the acid that nearly did it or the detonation. Jii had to take him to the hospital for that one--all hush hush, of course, and he never knew how Jii managed to keep it off the record books and covered up. (If he ever had any doubts his mother knew about his other life, it was dispelled that night. Even Jii wasn't that good alone.)
But some things he couldn't do from scratch--the raw materials for his tools, the base chemicals for his alchemy. And those...he had to acquire. By highly illegal means, of course--one didn't purchase several hundred pounds of dangerous chemicals, tools, explosives, and such illegalities from the local convenience store.
He tried to keep his act as clean as he could, but he harboured no illusion that others do the same. Couldn't--this was illegal, after all.
So Kaito swallowed a second time and made his payment to the smiling businessman moonlighting as an explosives smuggler, and tried not to think about the ways that money can be passed down the hiearchy and how many times it'd switch hands. Would it further some poor soul's meth addiction, or fatten the pocket's of some pimp caning the prostitutes under his foot? Did it help provide the budget for secret marijuana plants, sold to some lunatic who'd cut through everyone to get to his drugs, only stopping until he wakes up the next day in a pool of his vomit and do it all again?
He didn't know. He didn't want to think about it. But he could never shake the feeling that perhaps it wasn't all worth it, every time he sees his sellers' smiling, greedy, satisfied faces, and wondered if he really was any better than them.
He tried to keep his act clean, to promote fair play. A gentleman thief, after all--like Lupin. Phantom thieves had honour.
In reality, he had long lost his, and any credible claim at innocence.
His tuxedo was the only part of him that he could keep clean.