Remember how the letter Pluto had at the end of KH1 was never touched upon. I think I know why, it wasn't a real letter. Here's what I think happened. The last time we see Pluto with the gang in kh1 is when he is in traverse town. He is then seen again in that grassy field and shows up again in kh2 lost in the world that never was. After that we know what happens to him. In kh:coded we are shown that Pluto enters a corridor of darkness where a whistle is heard. Now we know from 358/2 days that the organization wanted Sora to lose his memories in castle oblivion so that he would never wake up. So now that they had Pluto they gave him a letter with a forged seal and sent him back to the realm of light to lead sora to CO. After Sora got close enough for Marluxia to lead him the rest of the way, Pluto was called back into the corridor and was trapped in TWTNW until Axel let him out after he went rogue.

 

That's my theory

Remember how the letter Pluto had at the end of KH1 was never touched upon. I think I know why, it wasn't a real letter. Here's what I think happened. The last time we see Pluto with the gang in kh1 is when he is in traverse town. He is then seen again in that grassy field and shows up again in kh2 lost in the world that never was. After that we know what happens to him. In kh:coded we are shown that Pluto enters a corridor of darkness where a whistle is heard. Now we know from 358/2 days that the organization wanted Sora to lose his memories in castle oblivion so that he would never wake up. So now that they had Pluto they gave him a letter with a forged seal and sent him back to the realm of light to lead sora to CO. After Sora got close enough for Marluxia to lead him the rest of the way, Pluto was called back into the corridor and was trapped in TWTNW until Axel let him out after he went rogue.

 

That's my theory

I don't know, I doubt Pluto would follow the whistle of just anybody. The only times he would would be if it were from Mickey himself or Riku, who he recognizes as being a friend of Mickey. I mean, he is still kind of a silly dog, maybe he could have been mislead, but I don't know, it's left too open for me.

Huh, that's actually a very curious theory you have there! That means that Pluto would've accidentally lured Sora and friends into harm's way! I mean, it's not the dog's fault, he doesn't know what he's doing, ya know? So you could be onto something!

 

Unless Pluto is really the 13th vessel for the true Organization...

pluto is a xehanort confirmed

 

i'm gonna say it was a detail nomura had not completely thought out. at the time it probably seemed like a good way to end KH, by leaving the viewers wondering what new lead Sora and co. were about to stumble upon on their journey to find Riku and Mickey.

 

the scene was probably included in CoM for consistency.