If you've seen Apocalypto you might have acquired an exaggerated sense of the importance of the Mayan sun god within their pantheon, but his twin areas of expertise must have seemed comparatively important during the two great crisis moments for the Pre-Colombian Maya - the collapse of their Classic civilisation (due largely to unfavourable environmental conditions) followed a few centuries later by the arrival of the poxy Spaniards.
Ah Kin likes to spend his evenings in the murky Mayan underworld; Xibalba. He had a companion dog to help him find the eastern horizon and while he's down there he merges with the nocturnal jungle cat to become Balanke, the 'Jaguar Sun'.
In his youth he was something of a looker (presumably before he developed those t-shaped incisors and crossed eyes) and had a thing for Ix Chel, the future Moon goddess. The pair are said to have invented sexual union and became patrons of match-making and procreation until Ah Kin assumed his full responsibilities as sun god, a position which came with a fiercer, less approachable aspect and the requirement to act as the bringer of doubt.
His union with Ix Chel persisted, and together they also became associated with sorcery and medicine. After the conquest however, her identity was quickly blotted out by that of the Virgin Mary.