Ideally, they go on to become fused in imagination. Like peanut butter and jam. Wine and cheese. Ketchup and fries.
To a point where the idea of one without the other seems utterly preposterous.
"There is,'' reckons Flames GM Brad Treliving, "a little bit of a big brother dynamic going on in this case.
"Although Hanny's experienced in the league, already three years and approaching 300 games, he's still, at 21, a baby.
"So Travis is that big brother figure ("Yeah,'' concedes 28-year-old Travis Hamonic, with an exaggerated eye roll, "suddenly I'm the old guy …").
"Right from Day One, when we made the deal, the next day I talked to Hammer and told him: 'Hey, we're a long way from training camp but the plan is for you two guys to play together.' And he was on board with that right away.
"We still had to sign Noah, of course, but they were still talking and texting almost immediately, already building that relationship.
"That pairing has been very good ever since China. I thought they were really good (Thursday) night (against San Jose).
"They share a lot of important traits but they both have individual strengths, as well.
"Yin and Yang."