Warning: Contains SPOILERS for Better Call Saul and Breaking Bad!
Lalo's fate on Breaking Bad provides a hint at his future with Jimmy. Introduced near the end of Better Call Saul season 4, Eduardo "Lalo" Salamanca (Tony Dalton) is one of the most dangerous of the exceedingly violent Salamanca cartel crime family. Stay on Lalo's good side, and he can be a friend, but cross him and death is usually on the menu. For now, Jimmy and Kim don't appear to be on Lalo's list of targets, but that could change if he ever finds out that they lied to him.
During Better Call Saul season 5, Lalo employed the legal services of a not exactly willing Saul Goodman after being caught by the police for a senseless murder he committed. Lalo then charged his new lawyer with retrieving millions of dollars in bail money from the desert, which saw a terrified Jimmy almost die in the process. Jimmy only survived thanks to help from Gus Fring's hired gun Mike, forcing him to lie to Lalo later about what happened. With Lalo secretly still alive after a botched assassination attempt, Jimmy's lie hangs over him like the sword of Damocles, even if he doesn't currently know it.
The character Lalo Salamanca was first set up by a seemingly throwaway line in the Breaking Bad episode that introduced Bob Odenkirk as Saul Goodman. In Breaking Bad season 2, episode 8, "Better Call Saul," Walt and Jesse kidnap Saul, who assumes they work for Lalo. He begs for his life, calling himself a friend of the cartel and trying to pawn off blame for something on Ignacio. One presumes that refers to Ignacio "Nacho" Varga, who shockingly died in Better Call Saul season 6, episode 3, "Rock and Hard Place." That same Better Call Saul episode teased Jimmy possibly revealing his knowledge of Lalo's crimes to the authorities, which would perfectly explain why he's so terrified of Lalo by the time of Breaking Bad. If he ratted on Lalo and Lalo ever found out, that would mean certain death.
At the present stage of Better Call Saul, Jimmy and Kim don't seem too keen on Jimmy spilling his guts to the district attorney's office. Yet, once Lalo properly reasserts himself into their orbit, it's not at all hard to imagine Jimmy being so terrified for some reason or another that he decides talking to the D.A. makes sense. One thing in question, though, is what exactly Saul means in Breaking Bad when he tells Walt and Jesse that it wasn't him, it was Ignacio. Nacho is dead, so he obviously can't do anything else to Lalo. Perhaps Lalo comes to believe Saul/Jimmy had inside knowledge of the plan to assassinate him — he did, but only in the most basic sense — and that's why Saul is so scared that he's after revenge.
That said, if Lalo were to ever find out Saul/Jimmy betrayed him, his vengeance would likely be swift. Considering Kim isn't seen in Breaking Bad, it's sadly possible that instead of getting revenge on Jimmy, Lalo rips his heart out by killing Kim, leading Jimmy to become the true scumbag he appears to be later on. With 10 episodes left to air of Better Call Saul season 6, it's only a matter of time before the Lalo shoe drops on Jimmy.
Better Call Saul releases new episodes Mondays on AMC.