Warning! SPOILERS for Better Call Saul season 6, episode 3.
Better Call Saul season 6, episode 3 sees Jimmy (Bob Odenkirk) and Kim (Rhea Seehorn) further descend towards their downfall, but their fate was sealed by their first onscreen date in season 2. In the AMC show's final season, Kim ropes Jimmy into framing Better Call Saul's Howard (Patrick Fabian) for "something unforgivable." Although they believe it's for the greater good (i.e., helping the Sandpiper Crossing residents), they are ultimately following the money and getting a lot of excitement as they scam a man they both despise. However, Jimmy and Kim's relationship is fueled by illegal excitement.
When Better Call Saul introduces Kim Wexler in season 1, she seems to have a borderline-platonic relationship with Jimmy, although they have shared some romantic moments in the past (as shown by season 1, episode 8 "Rico"). In season 2, Jimmy's life is at a crossroads - as he refuses the job at Davis & Main and law altogether - and Rhea Seehorn's Kim arrives to pull him out of the hotel pool. She wants to send him on the right track, but, instead, they end up forming a team (Viktor and Giselle Saint Claire) and scamming the obnoxious "wealth manager" Ken into buying them a whole bottle of the world's most expensive tequila. They then run off and share their first onscreen present-timeline kiss.
Jimmy and Kim's relationship blossoms as they become con artists together. The next morning after scamming "KENWINS," Jimmy asks Kim if it wouldn't be fun to do this every night. Throughout Better Call Saul's six seasons, the more Jimmy and Kim border on illegality, the closer they are drawn to each other. This is emphasized in Better Call Saul's season 6 episode 3. As the two propose ever more "audacious" ways of bringing down Howard, the distance between them decreases increasingly. When Jimmy plays Kim's game and returns the "audacious" remark, she can't help but kiss him. Needless to say, while this excitement makes the couple happy together, it will also be the catalyst of their downfall, especially Kim's, as her absence from Breaking Bad has had fans worrying for quite some time.
Jimmy and Kim's first onscreen date in season 2's "Switch" is also the moment Giselle Saint Claire emerges - Kim's Saul persona. In Jimmy's presence, Kim feels like a winner and, most importantly, she feels alive. Unlike Jimmy, Kim seeks both lives in parallel - the by-the-book lawyer and the witty con artist. By the season 5 finale, Kim has truly broken bad, even shocking Jimmy with her ideas for Howard. Huell's return in Better Call Saul's "Rock & Hard Place" (and his confusion as to why Jimmy and Kim keep "doing all this") shows Kim's dark transformation as a point of no return. In the last two episodes, she blackmails the Kettlemans and dissuades Jimmy from coming clean by asking, "Do you want to be a rat?"
Kim's change might seem sudden, but deriving pleasure and excitement from scams has been part of her personality for a long time, and it's not a consequence of her spending time with Jimmy. They both enjoy this life, and they came together as a couple in a scene truly symbolic of their transformation. Even the tequila bottle cap continues to make its way to the screen every season. Better Call Saul's protagonists' relationship is fueled by their con artist personas, and as season 6 brings the couple closer together than ever, it also announces a tragic end for the two.