Sai felt hollow-that's the only way he could describe the feeling. He knows he shouldn't feel that way; the war was over, Obito and Madara were defeated, and the nations were led to peace, but he couldn't feel any happiness. And the reason for that was for what he was watching not twenty feet away from him: The reunion of the original Team 7.
'Ugly' and 'Idiot' as he called them had thrown themselves at the traitor, tears of happiness falling down their cheeks. They were laughing with vigor, holding onto their former teammate tightly, as if they would never let him go. Sasukes' mouth was formed into a pout and a blush of embarrassment was present on his face, but he hugged them back in turn. Kakashi had limped over to the three teens and gave Sasuke an 'eye-smile' and an affectionate hair ruffle, causing Sasukes' blush to brighten.
Sai gripped at his chest, grasping his shirt in a tight grip. Why was Naruto and Sakura welcoming back Sasuke after what he did? After murdering Danzo or threatening to destroy Konoha? He looked back up and winced. Both of his teammates looked so happy, more free than they ever were with him. He remembered what Naruto had mentioned about Sasuke when they first met.
"Sasuke is the one who should be on this team! You're just the replacement until he gets back, so don't get too cozy around us, Sai!"
He had replied that he didn't want to be compared like Sasuke, but seeing them now, Sai would do anything to be in Sasukes' place. He watched with envy as he saw Naruto wipe his eyes of happy tears and clap on Sasukes' upper arm and as Sakura gave Sasuke a very light kiss on his lips. Another jolt came through his body as he saw the traitor wrap an arm around the pinkettes' waist and gave her one in return.
For the first time in his life, Sai felt like what he really was to Naruto and Sakura: a replacement.