Since “1923” began airing in December, audiences have been watching closely for connections and callbacks to the earlier “Yellowstone” prequel, “1883,” and many were delighted when they spotted Spencer Dutton (Brandon Sklenar) carrying a very prominent reminder of his late sister, Elsa (played in “1883” by Isabel May).

Sitting down virtually with Insider last week to discuss the “Yellowstone” origin story’s heart-wrenching finale, Sklenar said he was glad viewers had picked up on the fact that his character has a knife that once belonged to Elsa, as it was something he himself had suggested for the character.

The actor said that while he was having dinner one night with the show’s producers, they came up with the idea of making the weapon that Elsa was gifted from her Comanche tribesman husband part of Spencer’s kit.

“I felt like Spencer needed to have something from Elsa, and we kind of came up with the idea of having the knife,” he said.

Sklenar added that the thinking behind Spencer inheriting the weapon from his sister was to show the influence she had on him, despite the fact that Elsa was long dead before Spencer was born to James (Tim McGraw) and Margaret Dutton (Faith Hill).

Sklenar said it was also supposed to evoke the idea that Spencer “potentially first learned to track animals and to hunt with the Natives.” That means he shares the affinity for the Comanche tribe that his sister had.

As viewers of “1883” may recall, after the man she hopes to marry, Ennis (Eric Nelsen), is killed, Elsa meets the Comanche tribesman Sam (Martin Sensmeier). He helps her through her grief and the pair later become romantically involved, marrying in a tribal ceremony.

The two begin their friendship by challenging each other to a horseback race to see who’s the better rider. When Elsa beats Sam, he gifts her his knife, complete with its ornate leather sheath.

In the season finale, Elsa sadly succumbs to her wounds after being shot through the stomach with an arrow. It’s in an abandoned plain among the Montana mountains that she takes her last breath, and as a result, James and Margaret decide to build their house — which later becomes the “Yellowstone” ranch — there.

Sklenar said that building a rich backstory for Spencer was a big part of his process before shooting began on “1923.”

“Especially with a character like this, who is so internalized, so reserved, and really mindful about what he shows to people,” the actor said, “for me, that’s building and crafting specific memories.”

“So when someone is speaking about the war, I have specific memories from the war, and they’re real to me,” he said. “And when they’re speaking about my aunt, I have specific memories of her, and specific memories of my brother.”

He added: “It’s a really cool part of the job that I love doing, all this stuff that nobody sees. It’s fun.”