Ginger

Ginger and her elder brother Cain were with their parents on an expedition to explore the planet Charybdis, an Earth-like world with substances toxic to human life in its atmosphere.

When their vehicle crashed on a joyride, they were stranded hundreds of miles from base, with no way of calling for help; they tried to walk back overland, but their survival suits were not well equiped; as Cain tried to give the last of his air to his kid sister, the ground opened up and swallowed them both.

After a confused passage in the dark, they became aware of their surroundings: they were embedded in the innersurface of a gelatinous speher, opposite each other, their suits and other possessions missing and numerous fine white tendrils penetrating their skin. Thinking they were in the belly of an alien beast and about to be digested, they said their goodbyres to each other, then passed out...

They awoke an unknown amount of time later, on an unfamiliar part of the planet, with their bodies altered: able to breathe the atmosphere freely , they felt fitter thaan they had before, but were covered in fine fur (silver for Ginger and charcoal for Cain) as well as possessing tails, pointed ears and other animal-like charactersistics.