Who gives Percy the pen?

In "Percy Jackson & The Olympians: The Lightning Thief," Percy receives the pen, which is actually a magical weapon known as Riptide, from his friend and protector, Chiron. Chiron, who is a centaur and the activities director at Camp Half-Blood, gives Percy the pen to help him on his quest. When uncapped, it transforms into a sWord, serving as a crucial tool for Percy's adventures.