The "loyal monster" trope masks a fundamental divide between chosen obsession and programmed destiny. While Diablo operates at YPS-5 and Shalltear sits at YPS-3, the meaningful gap lies in their DNA's Growth and Darkness metrics. Diablo's low growth reflects a completed entity; his servitude to Rimuru is a sophisticated intellectual pursuit, treating the role of a butler as a high-stakes game of environmental curation. In contrast, Shalltear's high growth score is a scar. Her trajectory is defined by the psychological wreckage of her mind-control incident and the subsequent desperate performance of atonement to Ainz. While both exhibit low Ego, Diablo’s submission is an expression of his will, whereas Shalltear’s is a constraint of her code. This transforms the nature of their bonds. Diablo's relationship is a symbiotic obsession; Shalltear's is a fragile dependency. This comparison reveals that the defining horror of Diablo is not his continent-level output, but the fact that he actively seeks the role of a servant. Shalltear is a prisoner of her settings, but Diablo is a connoisseur of his own submission.