(Hmm… Well, originally, all he knew was that his father had been murdered and it had been made to look like an accident. Nothing else, really. Which was why the original motive was revenge on those who killed him, so he continued being Kid to draw them out. You say ‘watched’, and the anime makes it sound slightly different in all honesty, which I’ve said bugged me a bit before. Both versions didn’t mention revenge specifically, just finding out who killed him. Though… the specials did still make him sound angry, at least….

As far as the motive now… yeah, after he found out the reason Toichi was killed – interfering with a group of people looking for a specific gem – he shifted the focus more to stopping their goal specifically. Finding Pandora before they do and destroying it, hence why he largely only goes after large jewels. If he steals other things, it’s normally because he was either challenged or a specific reason comes up. If anything, it went from widespread to focused. In the anime, and in manga, though not focused on too much, would be when he helped out his mom sort problems out from her past. Stopping forgeries and  such isn’t his overall motive, but it gave a side reason for why he wanted to interfere with those two from the Ryoma heist.

Or, ya know. If you want Kid’s completely original purpose, it was mostly to stand out so much as to put Phantom Lady out of everyone’s minds. From there, Toichi must’ve come across Snake and co at some point and gotten on their bad side. As I’ve said before, Toichi and Kaito’s motivations for becoming Kid were vastly different, so… *shrugs* Kaito’s is still revenge focused, though. Just does side jobs.

I hope that answers your question, going based on what I know and remember. The rest is just a bit of rambling. And ranting.

…It’s so easy to find faults with how A-1 is handling this…. they pushed all the major episodes out quickly to explain everything as soon as possible for those who needed to know. Full motive at episode two. Two. Two. And then all sorts of character introductions. None of Kaito having time to get used to being Kid even with all sorts of chaos going on around him, settling into his job. And it has him immediately going to stealing the gems, and needing to have reasons for Kaito to steal items that originally had nothing to do with them. At the start of being Kid, Kaito didn’t know why his father was killed, just that it had to do with Kid. Hence why he stole all sorts of things, from gold boxes, to paintings, to statues… And why the police didn’t immediately write him off when someone said they were Kid and would steal a baseball. He stole everything. Wasn’t until the whole Pandora explanation that he went to jewel focused thief most people recognise from Detective Conan.

…Not to mention handling the episodes like this throws a lot of things in the story off, and leaves some characters hanging for quite some time after their introduction so that they can go back and use the material they wanted to use from the earlier chapters. *looks sadly at tantei-san*

And for those who haven’t read the manga… a little perspective.

Aoko had her date with Kaito – meaning her dad suspected him of being Kid – in the fourth chapter of the manga.

Akako appeared in the sixth, and that was only the time she tried to feed him chocolate to make him a slave.

She appeared again in ten, which was when she’d decided to try killing him instead. As some have said, this makes more sense for the cool-down time from when she obviously liked Kid after the first meeting, and feelings of jealousy that he doesn’t even look at her to build up.

Hakuba appeared in chapter fifteen. (and for even more perspective, this is in volume three. Of a currently four volume series.) Then again the next chapter.

And then the next chapter, seventeen, he’s convinced Kaito, whom he’d barely interacted with at this point, is Kid. Who knows how long it’ll be before Hakuba shows up for this, but it’s obviously going to involve a longer passage of time than the detective originally needed. Which undermines Hakuba’s ability quite a bit, imo.

Everything regarding Pandora doesn’t come into play until after all of this in chapter nineteen. During all that time, Kaito was literally not making any apparent headway in finding his father’s killers, and not for lack of heists. Sure, plenty of chapters weren’t heists, but more because he had no leads. And manga Jii isn’t nearly so helpful in the manga as he is the anime. Don’t get me wrong, I’m sure he assists Kaito at times, but it’s never a focus. Much more like ‘the man who was dad’s friend who’s willing to help’ than ‘Batman Kaitou Kid’s Alfred’.

Can’t really get mad at the others, Black Star and Phantom Lady, since Black Star was a flashback anyway, and PL didn’t have to be at an exact place per se. Did make people (myself included) a little irritated they brought Conan in for Ryoma after the Phantom Lady. It’s chronological to the heists, yes, but they should have shown Kid meeting Conan for the actual Black Star heist from the Detective Conan series. Else people don’t necessarily know this weird kid and the detective in the helicopter from earlier are the same person….)

/End rant