He was looking for his sister at the Tanner household when he came across Stephanie playing a song on her guitar. Jimmy liked the song and sat down to visit with her. They kissed, and then Kimmy saw them. Stephanie was stunned when Jimmy did the Gibbler gallops with Kimmy, and that is when Kimmy revealed that Jimmy was her younger brother. Stephanie was shocked and horrified that she had kissed a Gibbler.
At D.J.'s super fun barbecue party, Kimmy asked Jimmy to pretend to be D.J.'s boyfriend, but Jimmy had a hard time keeping up the facade because he had feelings for Stephanie. Stephanie initially rejected Jimmy, but she eventually gave him a chance and went on a date with him in his trailer where she didn't mind being, despite the fact that she thought he was going to take her to a fancy restaurant. Stephanie finally faced the fact that she had feelings for Jimmy, despite the fact that he was related to Kimmy.
In "Nutcrackers", their relationship hit a small roadblock when Jimmy was offered a job in Oakland, California (though he kept mispronouncing Oakland as Auckland), and also mentioned that he loved her, which overwhelmed Stephanie and caused her to avoid him. Jimmy left with his RV, causing Stephanie, with DJ's help, to examine their relationship. He returned on Christmas, surprising Stephanie when he showed up with presents which he bought for "Hanukkah prices".
- At 13 years old (S3E8 of Full House), Kimmy says her parents stopped having kids after her, so if Jimmy was born after this, they would be more than 13 years apart (which is actually closer to the actor's age)
- Jimmy's RV is named the Gibbler Galloper (S2E2), and he had a fryer put in because the RV does not fit through a drive-thru
- made up the compliment 'Rad-ajd', pronounced radish, meaning Rad Adjacent (S2E1 of Fuller House)
- has a U.S. centric map of the world, pinned with every place he's taken photographs (S2E2)
- had his photos in Nation Geographic (S2E2)
- "create[d] the illusion of a ghost using an elaborate series of pullies, levers, and electronic devices" (S3E5)
- can solve a Rubik's cube and play the flute (S3E9)
- is the paternal DNA of three viable embryos (S3E12)
- is a nickname for James (S3E12)
- is going to be a father (S3E18)