Lucas one weekend had gone back to the castle to go grab a few things, with Thomas and Edward tagging along.
It was not until Lucas had hit a switch on the wall on accident, and fell backwards into a room where he noticed something was off.
You see, for years the Charon family have had a machine that allows someone to go back in time, but it was only used to prevent things from happening but just changing the flow of time causing the events to change.
It also was discovered that this machine could also do a "return to the past" by the use of special time stones. These returns to the past reverse any time changes from roughly 24 hours of a change being noticed, and anyone who has visited the realm is immune from forgetting the events before and after and time change happening.
So appon Lucas booting up the machine (with two visible foot dust marks on the floor in the shape of shoes) he entered the realm with Thomas and Edward behind him wondering what is ahead.