As soon as Dosu hear Ren's voice he opened his eye wide and in a high-pitched voice scream "YOU BASTARD! What are you doing here?", meanwhile the other Oto ninja put their guard up, and draw their kunai ready to attack at any moment.
But Ren with a bored tone point his index and middle finger at the group then he swipe hit away while chanting "Bakudō # 1. Sai (Restrain)" causing the Oto ninja's arms to lock behind their back, then he draw his sword and finish them off by cutting the throat of their defenseless form.
Seeing his work Ren thought 'It is a lot easier, dealing with problems when you do not have to worry, about begin found out....wait how did Dosu recognize me as I'm still masked?' then his attention is once again taken by the guy on the hospital bed.
"To answer your question, while I was going back to the Konoha Stadium, I felt the presence of foreign ninja in the hospital, so I came to check the situation, color me surprised when I heard what was happening in this room, so tell me, how did you find me out? And why did you decide to go against Orochimaru?" at the end of his explanation ask Ren.
Dosu took a few seconds to reins in his anger at the individual that send him in this hospital bed and made him incapable of having children, and even if hearing his voice made him still feel pain in his lower region he took a deep breath and then explained.
"As for how I found you out even if you are masked is easy, sounds are my weapons and is thanks to them that I survived till now, I should be ashamed of myself if I didn't recognize the sounds of your voice after what you did to me, and Orochimaru used us only for his own benefit and I was tired of begin his tool and now it seems that he want to turn me into one of his test subject, now that you know, are you going to send me in the Konoha Torture and Interrogation Force? or directly kill me?" in the end asked a resigned and defenseless Dosu.
Ren and Dosu looked in each other eyes in silence for a few second then Ren removed his mask and said "I wanna make you an offer...I have seen first hand the result of what a powerful and degenerate man like Orochimaru can do, and unfortunately for our world he isn't the only one and not even the strongest one, so my plan for this is to create a group of like-minded persons from the various village, like a mercenary group who's main objective is to hunt down major criminal and help villages in dire need of help, so what do you think? Wanna join me? Benefit varies from me not killing you for attacking and threatening my sister, escaping from this difficult situation alive, having a chance to go against Orochimaru and others piece of shit like him, and I even heal you so you can get it up again"
Dosu once again looked at Ren figure and after thinking at his various option for a long while, he said "Can I take with me Zaku and Tsuchi?" and Ren replies "I'm sorry but they were used by Orochimaru as a summoning sacrifice" hearing that Dosu clenched his fist tight, then he relaxed again and said "I'm in".
Then Ren went near Dosu and used Kaido to heal his injuries, after that he gave him a sealed scroll with a Jigokucho and told him to use the chaos to escape the village and find a quiet place to recover and improve his skills.
Then Ren put on his mask again and went back to the stadium, noticing that the fights were over and the enemies were almost all gone, soon he reached the stadium a saw that everyone was on the roof of the central building surrounding the corpse of the 3rd Hokage Hiruzen Sarutobi who died with a smile on his face.
His presence was soon noticed by the others and was soon surrounded by Jiraya, Kakashi, Kurenai, Guy, Ibiki, Hayate and the other ANBU near and it was Kakashi who started by saying "I appreciate your help but who are you and what are you doing here?" but Ren did not want to talk afraid that he would be recognized, so he moved to take out the scroll with the 3rd Hokage's orders and sign but was stopped by the other ANBU near that pointed their ninjato at Ren's throat.
But before the scene could escalate, Hayate that recognized Senbonzakura on Ren's hip realized that it was his student and said "*cough*cough Wait, *cough*cough I know him, he is a mercenary that the Hokage secretly hired to help in the defense of the village, I was that one that was ordered to contact him *cough*cough"
Hearing that the ANBU lower their sword but keep their guards up , and Ren take that chance to pull out the scroll with the Hokage's sign and showed to everyone, seeing that they relaxed, then Ren went near Hayate and finally did the thing he wanted to do for a year but always held back, he use Kaido on him and healed him of his illness, then under the stunned eyes of Hayate-sensei that since ever for the first time he didn't cough "What?....I feel....good?!" then he took a blank scroll and on it wrote to send him the most urgent injured, and after he healed the most serious ones he used once again the Bakudō #26. Kyokkō (Bent Light) and changed back from his Shinigami persona, then he went on his way to met with Sakura and the two of them went back home in silence.
Two days after the attack on top of the Konoha Academy under the Hokage mountains everybody could be seen dressed in black giving the final farewell at Hiruzen Sarutobi on the front row there was Konohamaru crying in the embrace of Iruka-sensei while Ren was hugging his sister Sakura while he thought 'You were a peeping tom and your students are a drug, a porn and a gambling addict, but you were a good man and you have helped me and protected my family, so I promise you that I'll free your soul from that hollow as thankfully Minato has show that his digestion is really slow, just wait for me I'll send your soul to the Pure Land'
After that silent promise the ceremony ended and Ren and Sakura went back home, while the elder went to Jiraya to talk about the next Hokage and two individuals with long, black cloaks with red clouds, a chin-high collar and staw hats enter the village.