In tonight's episode of Superman & Lois, Clark showed his trust for John Henry Irons -- and the way he did so was a reinvention of one of the most frequently-referenced comic book scenes ever to take place between Superman and Batman. The reinvention is just that: it isn't a one-to-one translation of the scene from the comics, but instead an Arrowverse version of the same idea, played out in a slightly different way and featuring slightly different characters. Not only does it work out for what they're trying to do on Superman & Lois, but the reality is, one half of the original scene is Batman, who is not a part of the Arrowverse yet.
For readers of DC Comics who grew up in the '80s and '90s, there's no single scene that's more emblematic of the relationship between Batman and Superman -- and the trust and respect they have for one another -- than the moment when Superman gives Lex Luthor's Kryptonite ring to Batman and says, "You're the one I trust, if I ever lose it." That scene, after a fashion, shows up in tonight's episode.
Throughout tonight's episode, one of the key conflicts is the question of whether Sam Lane ought to keep the 7734 experimental Kryptonite weapon project alive. It's Sam who thinks it's time to retire it, having gained a new faith in Superman. For Superman's part, he isn't comfortable with the idea of leaving the world vulnerable to attack by Kryptonians, especially since his latest bout with mind-control brought him dangerously close to the edge. Lois can't understand Superman's point of view, creating a three-way argument with global stakes.
The solution? John Henry Irons. At the end of the episode, Superman took the key to the 4377 warehouse and presented it to John Henry Irons. Knowing that John had seen Superman at his worst and would know what to do in a desperate situation. That's what Superman was counting on when he asked Lois to call John Henry into action in the first place, and it's what drives his decision at the end of the episode -- to leave the key to the military's kryptonite stores with the only man Superman knows he can trust if the worst were ever to happen. It's a big sign of faith, and one that matches the one Clark made with Batman -- a character with whom he had a pretty contentious relationship at that point in the post-Crisis comics continuity.