Pierre is one of three possible characters who can help you get into Viper Manor. This is everything you need to know about how to recruit him in Chrono Cross: The Radical Dreamers Edition.
How to Recruit Pierre
Pierre can be found at Zappa’s Smithy when you’ve accessed Termina (Another World). If you approach him in the backroom, he’ll tell you that he’s lost his Hero’s Medal.
There’s a boy outside of Zappa’s Smithy running in circles, and he has the Hero’s Model. Head back to where you first entered Termina and talk to the man polishing the statue.
Now, go back to the boy and you can take the Hero’s Medal. Go back to Pierre and use the item while standing next to him (the button will depend on your console — it’s (Square) on the Playstation and (Y) on the Switch. Speak to Pierre again, and you’ll have the option of him joining your party.