Geralt first meets Jean-Pierre on the landing in the swamp as part of The Wolf Contract in Chapter II. Jean-Pierre hopes that bringing in these wolf pelts will secure him the coveted position of Royal Jägermeister, otherwise he plans to become a mercenary. He also relates a brief tale of Leo Bonhart (a character from the Witcher series) to Geralt. This is however, not the last time they meet.
The two meet once more in Old Vizima, in Chapter V, as part of Mud and Velvet and The Bruxa Contract. It appears that Jean-Pierre is an acquaintance of Antoinette, whom Geralt meets at the Royal castle.