It’s difficult to imagine anyone other than John Stamos playing Jesse Katsopolis in Full House, but another actor was vying for the gig back in the 1980s: David Duchovny. One of the original cast members of the classic family sitcom, the Tanner girls’ uncle was known for his rocker aesthetic, not to mention cool catchphrase “have mercy.” Over the years, his hesitation over being a parent figure to his nieces gradually changed as he became an active participant in their childhoods.

Full House‘s spinoff, Fuller House, brought back Stamos as the beloved Uncle Jesse to the delight of many fans. The actor joined the show’s core cast, without Michelle Tanner actresses Mary-Kate and Ashley Olsen. But unlike their roles in Full House, Jesse and the rest of the adults weren’t series regulars in the spinoff, with the focus instead on DJ (Candace Cameron-Bure), Stephanie (Jodie Sweetin), and Kimmy (Andrea Barber). Still, the producers made sure to bring them back regularly every season.

Overall, Stamos played Uncle Jesse for 13 seasons – 8 years in Full House and an additional 5 in Fuller House. Fans have seen the character mature and develop a sense of responsibility without losing his rock-n-roll mentality, not to mention his vanity. He married Rebecca (Lori Loughlin) and had twin sons in Alex and Nicky; he also worked his way up the music industry ladder by being the composer for General Hospital. However, had things turned out differently, Full House and its spinoff would’ve had Duchovny playing Uncle Jesse. It just turns out that the producers were dead-set on casting John Stamos for the part.

Duchovny auditioned for the role of Uncle Jesse in the original sitcom during the late ’80s – the actor himself revealed this during a guest appearance on Jimmy Kimmel Live!. He recalled that, at that point in time, he was desperate for any job, so he also auditioned for Danny and Joey, which ultimately landed on Bob Saget and Dave Coulier’s laps, respectively. According to Full House creator Jeff Franklin, however, they were set on casting Stamos for the role of Uncle Jesse. In fact, he didn’t even have to come in for a screen test as he was personally sought out by Franklin.

While Duchovny didn’t land any role in Full House, his big break would come just a few years later when he was cast as Fox Mulder in The X-Files, opposite Gillian Anderson’s Dana Scully. The Fox procedural series originally ran for 9 seasons – a year longer than Full House, although its revival was only on the air for two, compared to Fuller House‘s five years on Netflix. Nevertheless, what Full House did for Stamos’ career, The X-Files did something similar for Duchovny’s.

The role of Uncle Jesse is arguably the most important one in terms of gauging the success of Full House. Stamos is naturally good with kids, which made his interactions with the young cast, particularly the Olsen twins, very effective. This is still evident in the few times that he interacted with the children in Fuller House. So while Duchovny is a great actor, Franklin and the producers ultimately made the right choice casting Stamos instead.