#sandaime

But why have we not seen Sasori use Komushi's puppet? My theory is that Komushi's death was too sudden, the body too "fresh"...and it eventually decayed and fell apart. And so Sasori started developing new methods to "prepare" a body for his art.

Starting with small animals, like rodents and "lost pets", he experiments with different recipes until he finds one that works reliably, however the process is very slow. And so he basically gradually poisons Sandaime to death, who trusts and cares about him like his own son.

Sasori deserts the village while everyone is preoccupied with Sandaime’s declining health, so no one notices he is gone until it is far too late, and proceeds to raid nearby tribes and other satellite villages, finding victims to perfect his puppetry art and build his arsenal before returning to retrieve his magnum opus. 

The reason there was a whole year between Sandaime's disappearance from the Kazekage mantle and Rasa's ascension to the title, was not because the village was "searching" for him, but bc everyone hoped he would recover. When it became evident that he wouldn't, Rasa became Kazekage.

When Kakashi eventually leaves ANBU, that's when things really start going to shit. Once he finally manages to surface a bit from his depression (to an extent) he takes one look at the kid and goes "that's not Minato's kid what the fuck." Cue him absolutely tearing ROOT apart in his search for Naruto and coming out the other side going, "oh ok so the Hokage isn't stupid he just doesn't care. alright." He seriously considers assassination attempt #2 but doesn't know who else could take over. So after basically tearing Konoha a new asshole and leaving the Hokage to deal with the upset and Danzo, he 'requests' to visit Jiraiya in heavily implied language as he is sure the Hokage must have sent him there to be protected. (A solid plan worthy of a Kage and Kakashi isn't happy he wasn't in the know but whatever)

So Kakashi finds Jiraiya and basically has a minor panic attack when he realizes that Naruto isn't there either. I think this also might be the point where he starts to try connecting the dots on the idea that the Hokage isn't actually aware that the 'Jinchuuriki' isn't actually Naruto. So he bolts back to Konoha after a spectacularly awkward conversation with Jiraiya -- who is exceedingly confused about the whole encounter and just glad to be in one piece afterward -- and Kakashi starts digging into the paperwork. Iruka is immediately on his ass, traking what he knows and trying to figure out why Kakashi would be interested in Naruto. The two play a high-stakes cat-and-mouse game via paperwork until Iruka starts to realize all that Kakashi has done to try and find Naruto and realizes that it wasn't at the Hokage's behest.

So Iruka actually makes contact with with Kakashi, realizing that he could be an ally rather than the ruin of everything. Slowly Iruka learns the concerns Kakashi has about Naruto's safety and the valid political concerns of a Jinchuuriki-less hidden village. (I'm not saying they scheme to kidnap someone from another village but it'd be funny if Iruka got Gaara and the villages played musical Jinchuuriki, acutally managing to put most of them in better situations. And confusing the hell out of the Akutsuki.) Iruka melts like butter at the genuine care Kakashi seems to have for his sensei's son even if he hasn't been around until now. Kakashi gets close enough that Iruka tells Ayame to request Kakashi for her annual trip to the capitol. Ayame is a customer service master and can lie with the best of them and is able to play it off as a crush on the new ninja seen about town (since Kakashi was basically a non-entity before now). Kakashi takes the mission at Iruka's insistence, and brings Kakashi to meet Naruto. Though I'm 100% sure Iruka chakra seals/barrier seals the hell out of Kakashi before the big reveal.

If Iruka has played his cards right, then he is able to imply that this is all done on the Hokage's orders and Kakashi accepts it because that makes way more sense than a Chuunin and two Ramen Chefs being able to pull one over on the Hokage. Iruka also implies that Kakashi has been brought into the 'op' and thus Kakashi becomes Naruto's new big brother as he is apparently a 'ninja chef' that started working with Ayame at Ichiraku. Iruka might also imply that Naruto can know about his parents and Kakashi fucking clams up and flees. He does come back a year later though as a part fo the 'op' and actually tells Naruto about Minato and Kushina. He doesn't mention the 4th Hokage thing and never the nine-tails thing as they are village secrets (though Naruto has been aware of his 'passenger' for years by now).

Naruto obviously thinks a ninja chef is the coolest thing he's ever heard of and wants Kakashi to teach him. Kakashi 'understands' this to be his part of the 'op' and teaches him some basic chakra control exercises as well as leaving some basic fuuinjutsu scrolls. He is called to the Capitol again within a week because the Daimyo is convinced an enemy ninja has been terrorizing the town. Its really just Naruto attempting too much fuuninjutsu. Kakashi sits him down for a serious talk about limits and then tracks down an actual enemy agent to present to the Daimyo.

Throughout the following year, Kakashi takes a lot of missions in or passing though or by the capitol. This has the unexpected side effect of the Daimyo taking a shine to him and the Hokage more seriously working to develop him as the successor. I like to think the whole charade/comedy of errors (via iruka) ends with Kakashi watching the Hokage finally realize that the 'Jinchuuriki' in Konoha is a fake and internally panicking only for Kakashi to be like 'wait what about the op?' and casually explain Naruto's location and 'progress' with chakra and fuuinjutsu. And Hiruzen who has executed Danzo at this point and watched Kakashi single-handedly find the unknowingly lost Jinchuuriki and lay sweeping change to Konoha via the Daimyo's ear and ANBU contacts, just quits on the spot going "ah you have passed the test" and then fucking off leaving Kakashi with the hat. Like a week later I like to think that Tsunade fucking punts Jiraiya through the office door and demands to know what the hell is going on that Jiraiya is panicking over Naruto being missing/dead, only for Kakashi to go "oh thank goodness" frisbee the hat onto her head and dip.

500 miles to the Capitol and closing: a pissed and embarrassed Kakashi followed by a livid Tsunade, followed by a concerned Jiraiya, followed by an exhausted Tenzou seriously considering resignation