On the surface, Jamie is a humble mailman living in the sleepy town of Beach City. His only remarkable claim to fame is that he's the only courier who delivers the mail to Steven's house, if not the only one who knows where he lives! But Jamie is a dreamer and what he wants is in tandem with his larger-than-life personality. Jamie is an aspiring actor who hopes to make it big in Kansas City, the place to be in if you want to be a star.
Jamie left Beach City at one point to try and secure a job as a professional thespian, but returned months later claiming he missed his hometown. In reality, he was constantly rejected, crushing his heart. He's a good enough actor that he hid his vulnerabilities, but his desires subconsciously manifested when he fell forGarnet upon first sight. Though he tried to woo her with his usual dramatics purple prose love letters, proclaiming his love during a thunderstorm, etc. Garnet was relentless and told him under no circumstances would they ever be a couple. Jamie was heartbroken, but understood his forceful pursuit was unjustified. Garnet gave him a pep talk though and told him to put that passion into his talents and start small - like community theater.
Jamie's theatrical personality means he oversteps his boundaries and views the world romantically, so he's a bit overambitious. Once he's brought down to normal, Jamie proves he has the chops to be a good actor someday. Until then, he's having a ball working in Beach City's local theater.