He was waiting for the news in his room. He wasn't much worried though and was pretty confident that Orochimaru will agree to his proposal.
It's impossible that Orochimaru didn't know about the true capabilities of Sharingan, with him being from the Konoha and all of that. And here he was offering him an Uchina vessel on a silver platter.
Kimimaro was pretty much useless to him right now so he had nothing to lose by allowing him to go there.
And the only reason why he was going after Kimimaro's body up until now, instead of an Uchiha's body, was that Kimimaro's was at the palm of his hands the whole time, while he had to go through a lot of difficulties to get an Uchiha vessel.
And not like the Kimimaro can betray him once he gets to the Konoha. His spying identity and the whole infiltration plan and infrastructure there lies wholly on Orochimaru. Orochimaru could probably implicate him too if he wanted.
Kimimaro himself also didn't want to betray Orochimaru because he had a lot more valuable stuff to take from him. He didn't just join him for his genetic research. There were also many other valuable things he can get from him too.
And that's where he lied to Orochimaru. He wouldn't give him an Uchiha vessel for free of course. He would trade it for the information on his Snake Sage Mode, and that other thing that could be useful later on as well.
Everything was planned from the moment he appeared in that cage. He was thinking 10 steps ahead already in his head.
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I was right again this time. Kabuto appeared in my room with a grin on his face and said: "Lord Orochimaru agreed with your proposal. Let's go over there to discuss the details. But I really didn't know you were that smart too, no hard feeling between us, okay?".
I said: "Of course no, I also hope that you aren't mad at me for taking your spy job, right?"
He laughed a little and said: "In fact, I need to thank you for that. I've been doing that spying thing my whole life. I need a little break too. Konoha also holds a lot of bad memories for me. And I would also prefer if I could stay here and spend time and learn more from Lord Orochimaru. So, I'm thankful to you for allowing me that".
"No problem, as I said before, everyone wins in the end" I replied as we arrived at the Orochimaru's office.
Orochimaru looked me the same way as usual, but now with a little bit of apprehension in his look than before. He gave me a file and said: "This is your new identity. Kabuto will also teach you the art of spying for the next few weeks. Everything there is to know about spying, he will teach you".
He then said a little threateningly: "I expect that vessel you promised soon, don't disappoint me".
"Of course Lord Orochimaru. If I say that I will do it, I will do it. Thank you for putting your trust in me", He said and left the room together with Kabuto.
He later read the file Orochimaru gave him in his room and found out that outside of providing Orochimaru with the next Uchiha vessel. He would also have the Kabuto's job from the original series in providing him the information on the new genins that are coming.
His new identity was also Kabuto's original one from the series. He was found by the medical ninja named Nono as a boy and she adopted him. Later she died and he became an orphan.
Kabuto was originally going back to Konoha after the Otogakure conquest. But now it seems that the Kimimaro took his place. Kabuto was originally genin pretending to be sick so he could help Orochimaru a couple of weeks with the conquest of Otogakure and then he would go back.
He left through some very narrow secret tunnel in Konoha's sewer system. Only Orochimaru knew about that tunnel. And that's how Kimimaro will go in too. He will also have to wear eyeglasses, erase those 2 red dots on his forehead and adopt that Kabuto nerdy look for some time. Of course, change the name too...
He also modified the bones in his body to go to Kabuto's original height.
After some time. he will gradually change into his original Kimimaro look. They already had the same hair color. And he will later ditch those ugly eyeglasses and wear his original eye color and say those were the contact lenses he made if someone asks him. Not like they will pay too much attention on some unknown little genin.