Star Trek: Discovery actor Doug Jones says Saru might become a captain one day, but right now he's just not ready. Jones (who recently starred in Guillermo del Toro's Oscar-winning fantasy The Shape of Water) is well-known for taking on challenging roles that require a lot of time in the make-up chair, and Saru is no exception.
The Discovery's first officer is a Kelpien - a species designated as prey on their own planet, who evolved to have heightened awareness of danger, detected by tendrils on the back of their head called 'threat ganglia'. As such, Saru is naturally excellent at spotting potential trouble, and even served as acting captain of the Discovery during Captain Lorca's absence in season 1. After it turned out that Lorca was actually an evil doppelganger from the Mirror Universe, Saru then served under another evil doppelganger from the Mirror Universe - Philippa Georgiou.
Given the Discovery's poor track record with captains, and Saru's role in ending the war against the Klingons (for which he was awarded the Starfleet Medal of Honor), you'd think that he would be due a promotion. Instead, the Discovery heads to Vulcan to pick up a new captain - though since their journey is interrupted, Saru will still be acting captain when season 2 begins. However, speaking in an interview with Screen Rant, Jones said that he prefers Saru in a supporting role:
"I think the character of Saru, I mean he very much wants to be captain. He's been on that deck for so long in the command track and as the first of his species to have gone through Starfleet Academy and have come out as a high ranking officer on a Starship, he's the first of his kind to ever even come close to this, so he's got a lot to prove and he's got a lot to say. But, me personally, as Doug Jones the fan of Star Trek, I think the dynamic of that character works very well as a first officer; as second fiddle to a captain. And that's me personally."
Saru has been shown to be extremely ambitious and determined to perfect his leadership skills. In the season 1 episode "Choose Your Pain," he asked the Discovery's computer to compare his own performance as acting captain to the records of Starfleet's most decorated commanders. However, after his tough decisions led to the Discovery's resident tardigrade almost dying, Saru canceled the performance review, saying solemnly, "I know what I did." After that Saru showed more humility, and Jones says that the Kelpien still has some way to go before he's ready for a permanent captain position:
"I think [Saru will have] the captain's chair one day. Early on, we're only about to start filming season 2, there's still a lot of room ahead of us. So I think for now, he still has more to learn in the leadership department and the courage department under a captain who's been there and done that a lot, a seasoned captain."
Of course, the identity of the Discovery's next captain is still unknown, so Jones may be dropping hints with his mention of "a seasoned captain." Unfortunately, we'll have to wait until fall to find out who will lead the next step of this journey.
Star Trek Discovery season 1 is out now on home video. Season 2 is expected to premiere in early 2019.