Tony has been upset for days about the salt. He's retreated to 'sulk' mode, which means he spends most of the day at the College doing repairs or engrossed in work, and then spends most of the night cooped up in his lab at home. He has not been good company, but at least he's been productive.

When he'd tried to scarf down something resembling a meal today in between projects, some of his coworkers had gently suggested that he take a real break and maybe go out to get some lunch - he'd taken that to mean that his bad mood was bringing everyone else down and they wanted him to go blow off some steam before trying to get any more work done. He can't say he blames them. So he trudges home, even though he doesn't really want to, and pulls some leftovers out of the fridge.

He's sullenly picking at the last of his food when he hears a knock on the door. Tony sighs.

"Yeah, what—" he begins, opening to door. And then he immediately forgets both his bad mood and the rest of his sentence.

"Dad!" His face splits into a giddy grin, and he flings his arms around his father. "You're back!"