Sometimes even dumb and bad jokes were needed to keep the mood just light enough to not send everything into complete ruins. Tony was sad but he didn't want to set the library on fire and bring everyone down with him just because he was. Natasha certainly didn't deserve it.
And Tony knew. He knew he needed to look at the big stuff. That was what he normally did, he took the big picture and turned it around at every angle to try and see what was coming next and how to best prepare for it. So he knew it. He just -- in this instance, want to see it. Because as much as he was aware that life and the universe were governed by random circumstance as opposed to divine plans, or those laid by important men and women, it bothered him. It bothered him to know that there was nothing he could have done to have this moment be any different than what it was. It felt like giving up, and that wasn't something Tony did.
He did not mention the fact that they did not know if his plan in the future worked. Not even for his sadness would he ever admit uncertainty over that, because that would mean that Natasha might have died for nothing, and it wasn't a thought he was going to entertain.
Instead, he heaved out a sigh, clasped his hands together over his stomach. "Yeah," he said, because she probably wasn't wrong. "But he was like -- mine."