Warning: SPOILERS for Ozark's season 3 finale.
The shocking ending of Ozark season 3 was the series' best so far, but the cliffhanger begs a huge question: why did Omar Navarro (Felix Solis) choose to have Helen Pierce (Janet McTeer) murdered instead of the Byrdes? In the final moments of the Ozark season 3 finale, "All In," Marty Byrde (Jason Bateman) and his wife Wendy (Laura Linney) reluctantly arrived in Mexico along with Helen to meet with Navarro. But as soon as they got out of the car, one of Navarro's gunmen immediately blew Helen's brains out, splattering her blood over the Byrdes. Navarro then hugged the shocked Marty and Wendy, cementing them as "his choice" - but why?
The crux of Ozark's drama has always been Marty's efforts to protect his family from being murdered by the Mexican drug cartel he (once secretly) worked for. This meant relocating the Byrdes from Chicago to Osage Beach, Missouri in Ozark season 1 so Marty could set up business fronts in order to launder millions for Navarro. Once Wendy and their kids Charlotte (Sofia Hublitz) and Jonah (Skylar Gaertner) got involved in the family business, everything got more complicated, especially since Wendy had wildly different ideas from Marty. In Ozark season 2, Navarro's no-nonsense attorney Helen Pierce was introduced to keep the Byrdes in line, and she soon discovered how dysfunctional Marty and Wendy's marriage is. Still, Helen gravitated more towards Wendy, who set up the Missouri Belle casino as Navarro's new, "legitimate" business, which Marty ran in Ozark season 3 along with his Girl Friday, Ruth Langmore (Julia Garner). Wendy then wanted to expand and absorb a second casino - a plan Marty actively sabotaged since the Missouri Belle was under close scrutiny by the FBI.
In Ozark season 3, as Navarro fought a bloody drug war with a rival cartel, the working relationship between Helen and the Byrdes irrevocably fractured. The straw that broke the camel's back was when Wendy's dangerously bipolar brother Ben Davis (Tom Pelphrey) went off his meds and told Helen's teenage daughter Erin (Madison Thompson) the truth about her mother being a criminal. Helen marked Ben for death and essentially broke ties with the Byrdes. Wendy tried to save Ben but eventually realized she couldn't protect her entire family. She made the unthinkable call to have Ben executed by Helen's hitman but, regardless, Navarro's attorney set a plan in motion to steal Byrde Enterprises away from Marty and Wendy. By Ozark's season 3 finale, it was evident that Helen and the Byrdes could no longer co-exist and Navarro made the (questionable) choice to keep Marty and Wendy.
Obviously, the Byrdes are the main characters of Ozark, so they would have to survive, but why did Navarro pop a cap in his lawyer? Helen had served Navarro well for years and she was highly competent; she even withstood being tortured and never wavered in her loyalty. In fact, Navarro had just trusted Helen with caring for his children in the U.S. when the Lagunas cartel massacred everyone at Navarro's son's baptism. Meanwhile, Marty and Wendy have proven to be mercurial and endlessly problematic. Navarro even kidnapped Marty and held him prisoner for days just to glean what exactly Marty wanted.
The key that saved the Byrdes' skins is when Marty put Wendy's idea to make them "more valuable" to Navarro into motion by helping their employer win his drug war. Marty turned over the video taken by Jonah's drone of a Lagunas massacre of Kansas City mob employees on U.S. soil to his FBI contact, Agent Maya Miller (Jessica Frances Dukes), which set the federal government upon the Lagunas cartel. Obviously, Navarro was grateful that the Byrdes eliminated the existential threat to his business. But still, Navarro didn't have to kill Helen - he could have just transferred her since she made it clear she didn't even want to be in the Ozarks. Even if Helen wanted to destroy the Byrdes, she would have likely yielded to Navarro's wishes if he ordered her to stand down and go back to Chicago.
The case could certainly be made that Helen was the more stable choice to keep alive, but over the course of Ozark season 3, Navarro had developed a private rapport and respect for Wendy. And again, the Byrdes did eliminate the Lagunas as a threat to Navarro's life and business. At the end of Ozark season 3, Navarro was the one who decided to go "all in" with the Byrdes and he showed his gratitude by callously executing Helen, their main rival. But when Marty and Wendy flew to Mexico, the deck in Osage Beach reshuffled: Ruth joined up with Darlene Snell (Lisa Emery), who reignited her heroin operation and formed an alliance with the KC Mob. Even Jonah is furious at his parents over Ben's death. In Ozark season 4, Marty and Wendy will unwittingly return to find the Ozarks more hostile to them than ever - and Navarro may end up regretting choosing Marty and Wendy over Helen.