Natalie Odenberg was the Princess of Switzerland that started the catalyst of murdered Royals in Versailles. She was found by The Main Three when the door was left ajar and the stench of the room hit Dominic who then proceeded to call the man in charge, Gabriel. Daniel who was Gabriel's best friend at the time tagged alone, on their way to Natalie's room so was Elliot and once the door was open, it would never be closed. The grotesquee image they witness started a spark in the halls of the famous castles, no one could sleep after finding out that she was murdered by one of their own and that after the second attack nobody was safe.
After the death of his sister, the boys induced a plan to figure out how exactly the events in Natalie's room took place since Elliot for the life of him didn't believe his sister killed herself and if she did, not willingly. After the investigation they realized that yes, Natalie was indeed murdered but by who? Elliot wanted to avenge her death and when the boys created the Pact he rebelled against it however, his lips where sealed when he realized it would be easier to catch the killer in close circumstances. But his grieve took the best of him and Gabriel had told him he had to keep his main in check or he was going to blow everything. Elliot left Versailles for a while and came back more determined than ever.
The famous Pact, is a treaty the Royals in the Palace did to keep the Murderer and the Murders inside the Castle a secret from outside sources, like family memebers and presses. It brought big controvery within the walls of the Palace for it was unconstitutional that they'd keep a secret this big when it's a possibility that at the end of the day, they could be dead. However Gabriel told them that if the Royals were to go leave the murderer wouldn't be found and he or she would probably find other means to kill them or anyone else like their parents. Outside of the Palace, barely anyone question the disappearance since for starters, no one knew but there were suspicions as to why certain Royals weren't seen. However, no one can exactly know what happens in the Castle in close quarters. All the Royals are left to do now is survive and figure out the Clues the murderer had left for them.