Ben looked up at him, uncreasing the crease he'd just made. "Nope," he said, utterly solemn for a moment, the answer itself earnest and certain, because peeking the first time had been something he couldn't help himself from doing, but then he'd remembered their deal. They were going to do this together. It was what fathers and sons did.
"Can I open it now?" he asked, and even as he did, the small pocketknife Dean had given him was poised to slice through the top of the envelope. For Ben, there weren't concerns about the future, or expectations about a month or year from now, there was just the immediacy of this answer and the proof needed for him to be able to point at Dean and say 'that's my Dad right there'.
Because that was what the test had to say, it just had to. Even if Dean still wanted to be his Dad, even if Ben was allowed to call him Dad, it would never be fully right because Dean probably would have more kids someday and they'd be his kids and he'd just be the kid who everyone liked enough to let him pretend he was part of the family. It was bad enough this new baby was going to be a real Winchester and he was just the illegitimate kid. God wouldn't have made him even less a Winchester, would she?