'The Lord of the Rings' character who kept Sauron's ring is a major player on the Amazon show. Actor Maxim Baldry teases how he's headed down a path of 'retribution.'

• Warning: Minor spoilers ahead for "The Lord of the Rings: The Rings of Power."
• Insider spoke with Maxim Baldry, who plays the notable Númenórean man Isildur in Amazon's show.

In "The Lord of the Rings" tale by J.R.R. Tolkien, Isildur is one of many fallible human characters in a fantasy world where elves and dwarves and other mystical races of beings rise and fall in wars through the centuries.

For Maxim Baldry, who stars in Amazon's prequel series "Rings of Power," bringing Isildur to life started with learning more about the man's humanity.

"My knowledge of him before going into the show was that he didn't throw the One Ring into the fire — that fateful act that he did at the very beginning of 'The Fellowship of the Ring,'" Baldry told Insider over a recent Zoom call. "And then I dived deep into the books and found out that this guy wasn't just an evil, tragic character. He's had a lot of heroic moments throughout his life."

As detailed on screen in Peter Jackson's "Lord of the Rings" film trilogy, long after the events in "The Rings of Power" timeline, Isildur eventually succeeded in taking the One Ring from Sauron. But he failed to destroy it. Instead of following Elrond's urging to cast it into the fires of Mount Doom, Isildur kept the ring and was killed for it.

So audiences tuning into "The Rings of Power" on Amazon likely already know the tragic fate of this young Númenórean, adding a level of anticipation to the character as Baldry plays him.

How does this restless young man become the hardened leader who we know will fail to defeat Sauron forever when he finally has a chance? Or as Elrond put it in "The Fellowship of the Ring" movie, Isildur's actions will one day represent "the day the strength of men failed" and "evil was allowed to endure."

Maxim Baldry says bringing youthful nuance to Isildur was important for season one of 'The Rings of Power'

"I had the gift of bringing this guy to life and giving him a personality, making him as a relatable young sailor on the cusp of adulthood who's trying to find himself," Baldry said. "He's very vulnerable. He's grieving the death of his mother and he is not really opening himself up to anyone. There's no outlet for that. You see that in the breakdown of his relationship with his family, the way that he doesn't want to pursue his life laid out by his father Elendil."

When audiences meet Isildur in "The Rings of Power," he's struggling to find the right place for himself in Númenór. He's unsure of what he wants, but seems to know whatever he's seeking won't be found in the pristine city of his ancestors. While sailing with the Sea Guard naval army, Isildur hears an unknown voice calling to him from the shores of the island.

"It's fascinating to hear fan theories about it. Who is it? Is it his mum? Is it fate? Is it his destiny calling out to him? Is it the One Ring? What is it?" Baldry said. "I think exploring all of those things just make him such an interesting character to play because there is so much in store for him."

The actor says showrunners Patrick McKay and J.D. Payne have a very difficult task at hand, which is crafting a compelling storyline "that takes us from the place that we have started now to the place where we know we need to end," since we already know what ultimately becomes of Isildur.

Baldry says Isildur's arc in the first season of "Rings of Power" starts him off with a youthful naivety that will eventually shift into the warrior and future ruler we know he will become. The Isildur we're seeing now really struggles to communicate, making his relationships with people (his father Elendil, or his friends) more complicated. But that struggle vanishes when it comes to his horse, a noble steed named Berek.

"His love and affection comes through Berek," Baldry said. "His sense of self really opens up around the animals, maybe because he hasn't yet quite figured out the mechanism to work around humans."

The actor says even with these interpersonal failings, Isildur has a sense of duty and makes every effort to do his best within the Númenórean society.

"I don't think it's just simply him rebelling," Baldry said. "He is trying, but there's just something pulling him away. And what is that? And I don't know, it could be fate, it could be destiny."

"I don't really want to reveal the certain moments that drive him," he continued. "I want it to be up for interpretation because I think that is what makes him so interesting, is that he isn't a black and white character — there's nuance to him."

Baldry says we'll soon see something 'taken away' from Isildur that will set him on a path of 'retribution'

As of "The Rings of Power" episode six, which aired September 30, Isildur and several hundred other Númenóreans are in Middle Earth and mired in a dangerous battle against Sauron's minions. In the final moments of the episode, Isildur and his best friends and father were swept up by an exploding volcano in the Southlands — the future Mount Doom and land where Isildur will eventually face Sauron in battle.

But how will his character get to that point? We'll have to wait for more to unfold in "The Rings of Power."

"I really actually leaned into his youthfulness and his ability to make mistakes because I think he is going to go dark, you're going to see certain things be taken away from him," Baldry said. "And not to give any spoilers away, but it will force him down a path of ... what would be the right way to describe it? Retribution."

Baldry also teased a detail on his costume that some Tolkien-experts might want to take a closer look at (you can see it in the photo above).

"There is a Númenórean detail on the shoulder of his civilian costume," Baldry said. "It's Númenórean golden lettering. He'll learn in time how important that is for him. And I think maybe he takes Númenór for granted, but when he is wearing his Númenórean clothes, he is at home. That sense of home will be important for him down the line, even though he doesn't know it yet."

"The Lord of the Rings: The Rings of Power" premieres new episodes every Friday on Amazon Prime. For more on the series, see all the photos of each "Rings of Power" character compared to the actor in real life.