Six months later...
Data walked down the corridor, his steps still slightly clumsy. This body, though almost identical to his previous one, needed some getting used to. It was like wearing in new shoes.
He hoped B4 would like his present. It wasn't much, but B4 said he wanted to do more puzzles. Data entered the quarters he now shared with his brother and saw said brother staring out the view-port.
B4 turned and saw his brother at the door. He knew he should not feel sad, yet he did. Data had gotten a new body, with Commander Maddox' help. He had seemed very willing to help them when he realised what was happening. Data threatening to tell Starfleet Command that Maddox had not fully investigated the source of B4's 'schizophrenia' before diagnosing him unstable might have helped with that.
He was happy that Will and Deanna were going to have a baby girl. He was very happy to learn that they planned to name her Natasha.
He was happy that Geordi was happy. After Data came back, B4 had seen him smile a lot more.
He was happy. He had so much to be happy for. And yet he was sad.
"I have a gift for you brother." Data said, coming forward and sitting opposite B4. And B4 realised why he was sad.
He missed the closeness he had shared with Data when Data was only in his head. He missed having Data all to himself.
But as he looked at the object Data was holding, he realised he had lost nothing. So he spent the rest of the day with his brother, learning how to play with the Rubix Cube.