The Sun
"Parabola-linen crumbles in sunlight. The mushroom wines of the Neath are not kindly received in the wine-shops of Italy and France. Prisoner's honey loses all its virtue."[1]
The Sun is the Judgement of the Earth and of Mankind - at least for those dwelling on the Surface.
Vitamin D
To Surface-dwellers, the Sun is a benevolent force, even one worthy of worship. But to more... informed individuals, the Sun's virtue is questionable at best. It is brutally effective at enforcing its laws; denizens of the Neath who have lived too long often drop dead or even disintegrate upon reaching the Surface, and most of the Neath's fantastic delights are reduced to their normal variety under sunlight. Parabolan entities are cooked almost immediately, as they too Are-Not. And stories about the Neath are simply not believed because of all this.[1]
The Sun does have a view of the Neath, in Aestival, where there's a gap in the roof. Despite its deadly effects, sunlight is highly addictive to denizens of the Neath (who doesn't love a warm summer day?) and many of them go out with a smile.[2] Denizens of the Neath who are severely starved of sunlight may enter a trance of sorts when exposed to sunlight in small quantities, such as through a Sunlight-Filled Mirrorcatch Box, causing them to chant an infamous mantra: "THE SUN! THE SUN!"[3]
Albion's murdered star is not the Sun, so we may believe that Sol is just fine in the Sunless Skies timeline.
Once Upon A Time
The Sun's story is that of fleeting desires and the horrors of love. Before even the First City, the Sun fathered the Mountain of Light with the Bazaar. Naturally, such a union was scandalous even for the stars, so the Sun stored Stone in the Neath to avoid execution. Then the Sun, being the cad that he is, fell in love with a different star, and had the Bazaar deliver a love letter to her. The Bazaar delivered it, and the other star rejected the Sun, so the Bazaar now bides its time to prevent the Sun from drowning in its own tears.[4]
