Hershel, sometime after the events of Layton's Mystery Journey.
The Laytonmobile's engine sputtered. Hershel patted the dashboard as it climbed over the hill. Months of travel and clandestine investigation had taken their toll, on him as well as his beloved automobile.
Not much further.
He parked on a side street a few blocks away, lest the car attract attention. The sprawling Victorian house was quiet and dark; anyone inside was likely asleep.
Sleeping and safe. Please. He shouldn't have come back—danger stalked him everywhere, these days—but he was so very, very tired.
He unlocked the door. The first thing he heard was the cuckoo clock Luke had picked out for their living room, calling the quarter hour. Nearly midnight. Hershel added his loafers to the line of shoes by the door (neatly polished mary-janes and brogues and a remarkably dirty set of combat boots) and started for the stairs. He would worry about explaining his presence in the morning…
"MREOW!" His foot touched something soft that exploded from beneath it and tore up the stairs. Hershel stumbled, bumping into the sofa. He hadn't even seen Flora's cat.
A light came on at the top of the stairs, followed by running footsteps and a dark silhouette raising a frying pan. "Who are you, what're you doing in here, and what d'you—"
The figure froze.
"Papa?!"
The next thing Hershel was aware of was the clatter of cast iron hitting the floor and his elder daughter all but flying to throw her arms around him.
Every worry that had weighed on him all these months melted away. "Flora… my dear…"
"We were so worried," Flora sobbed.
Second and third silhouettes materialized at the top of the stairs, unarmed with cookware this time. But Emmy had never needed a weapon to fend off intruders, and Katrielle had learned from the best.
"Daddy!"
"Professor!"
Hershel's knees went weak, but it hardly mattered with a three-way hug holding him up.
(Author's note: And then they make him tea and Kat calls Alfendi to come over right now cuz he got his own flat when he joined the yard and Emmy rings Luke in the middle of the night and Al rushes over and Luke starts crying when he talks to the professor on the speakerphone, and they all pile on the couch and fall asleep, and in the morning Luke rushes over there first thing and Lucy probably shows up at some point and they all talk Layton into letting them help with his case. And they all lived happily ever after.)