Alfendi Layton and Lucy Baker will show up in the sequel and have some clues to why Hershel Layton had left Katrielle and the puzzle she is left with.Alfendi appears to be older than Katrielle so he might have memories and clues on the reason Hershel would just straight leave his daughter and have a puzzle that questioning Katrielle family relation to Him.
- Still way too early for such a claim but since this is WMG, one has to remember the post-credits of Layton Brothers: Mystery Room. Commissioner Barton is an old man which he was not when Hershel was still active. Thus, Professor Layton himself became an old man by then and Alfendi is less than 30 years old. Assuming that Layton Brothers took place at the same time as Katrielle Layton's cases, it can be assumed that Professor Layton went on a case with some of the police members of Scotland Yard, thus his supposed disappearance. And that's why Commissioner Barton aside from Inspector Chelmey, Grosky and some others are absent as they are most likely pursuing the same case. Also, Katrielle already solved the riddle. She only just needs to find Hershel, wherever he is, and assuming that Katrielle Layton will have her own Trilogy. At the same time, however, the riddle "If you are not really my child, who exactly are you?" can refer to Katrielle being a reluctant puzzle solver, similar to Hershel himself when he was younger but like the two, they grow fond of puzzles as time went on.
- The anime jossed this as Katrielle managed to find her father on her own. Alfendi might appear later though if there is a sequel game.
Katrielle is Luke Triton's biological daughter.Hershel's last riddle, and the lack of any indication of a mother, make it seem likely that Hershel adopted Kat. Many of her key personality traits (Big Eater and Speaks Fluent Animal in particular) match up with Luke's during the earlier games. If Luke and his wife went missing, Hershel could have adopted their daughter and then, when she was of age, gone off to find out what happened to them.
- Carrying on from this, Kat's design seems to be a little familiar. Is it possible that Luke's wife is Flora? If she's Luke's wife/Kat's mother and she and Luke have disappeared, that would account for her absence from the game universe. This is also arguably suggested by the wording of that riddle. "If you are not really my child, who exactly are you?" Well, if she's Flora's daughter, that would essentially make her Layton's grandchild.
What little Sherl remembers does not refer to a location but to The Tower cardWhen Sherl asks Kat to investigate his past, he lists the things he remembers as: a tower, something (or maybe someone?) falling and lightning; all of which fits the typical design of The Tower in Tarot perfectly.