In the Season 2 finale of Locke & Key, Tyler Locke proves he's wise beyond his years when he tells his siblings he has no plans to use the Memory Key before his 18th birthday. If he stays true to his word, Kinsey and Bode will be living in a world of magic their big brother has no memory of when the show returns for Season 3. But while his plan is a noble one, having Tyler not remember magic is going to be hella complicated, and the show can't even use the Locke & Key comics as a roadmap for what to do next.

When it comes to adults remembering magic, the comics employ a device known as the Riffel Rule to keep grownups on the sidelines of the action. Created in the 1940s, the Riffel Rule is named for Hans Riffel, a spy who used the keys to harm others during World War II. The Locke family never wanted the keys to be used to hurt people, so they created the Riffel Rule Key. The key ensures that once a person turns 18, they lose all memory of magic.

The Locke ancestors based the rule on the idea that the keys are safest in the hands of children, who are less likely to use the the magical objects maliciously. But there are a few exceptions to the rule. For instance, if someone like the kids' father, Rendell, drinks too much, they may temporarily access their memories of magic. On the whole though, once a keeper becomes an adult, they have to leave the world of magic behind them.