Cat
Cat reliability operates on a spectrum ranging from 'absent' to 'aggressively present,' with no middle setting available. The cat may provide sustained comfort for three hours, then vanish for eighteen. It may demand attention precisely when you cannot provide it, then ignore you when attention is desperately sought. Scientific studies indicate cats recognise their names but choose selective response—a finding that surprises approximately zero cat owners. Yet within this chaos lies a strange reliability: the cat will, eventually, return. It may knock something off a surface to announce this return, but return it shall.
Nostalgia
Nostalgia demonstrates superior consistency in delivery but inferior consistency in quality. The mechanism fires reliably when triggered—hear the song, feel the feeling—but the emotional payload varies unpredictably. Some nostalgic episodes deliver pure warmth; others deliver warmth laced with melancholy, regret, or acute awareness of mortality. The Portuguese call this saudade; psychologists call it 'bittersweet.' Neither term suggests reliability in the comfort-provision sense. Nostalgia always arrives, but you never quite know what it's bringing.