The function of a "tank" in isekai is usually defined by health points, but the real divergence lies in how a character processes agony. Because one operates on a physical axis (YPS-2) and the other on a narrative axis (YPS-4), a direct power comparison is irrelevant. Instead, the contrast reveals a fundamental truth about suffering: the difference between pain as a reward and pain as a currency. Darkness represents a complete erasure of the "cost" of combat; her masochism turns the trauma of the front line into a personal win, rendering her endurance a punchline. Subaru, conversely, treats suffering as a brutal transaction. His Return by Death mechanism forces him to hoard trauma to buy a favorable future, transforming agony into strategic intelligence. While Darkness finds liberation in the blow, Subaru finds only the burden of memory. This creates a stark divide in their DNA profiles, specifically in Darkness and Growth. Darkness remains static because her desires are already met by her failures, while Subaru’s trajectory is a vertical climb fueled by the psychological wreckage of a thousand deaths. The narrative utility of a tank is not about who can take more hits, but about what those hits cost the soul. In this framework, Subaru's narrative weight dwarfs the physical resilience of a Crusader, proving that the true shield is not armor, but the willingness to be broken repeatedly for the sake of others.