first things first: Challenger has no intentions to harm that cub or Dys.
Now that's sorted; onto the explaination.

So Dys (going by the name Diessa) and Challenger are best friends. The best of friends and Challenger can get away with shit that literally no-one else can pull.
Dys IS a demi-god, and has powers over gravity and water (despite them yellow eyes) as well as all the perks of being a demi-god (incredibly slow/not visible aging, extreme strength when needed and top speed that is much higher than a normal lion. Norms - 50mph, Dys - 90mph WITHOUT gravitational assistance and is the same height as an average male lion).
The two of them formed an unlikely friendship over their mutual dislike of other creatures and their solitary ways, hard minds etc etc. Challenger loves a fight, Dys dabbles in genocide, the normal.
Either way; Dys never showed any interest of starting a family and Challenger couldn't even if she wanted to; she's barren.

The two of them share a territory which covers about 50 - 75 square miles (about half of what a full pride needs) and they defend it with ease. Saying that, they are often apart for days or weeks or sometimes, if one of them is in a particularly pissy mood; then might not see each other for a month or two; which is what the case was here.
Dys snuck off in her last months of pregnancy and vanished, but her scent markers where still there and refreshed regularly, so Challenger wasn't at all worried...until she came across a cub.

The cub would have been either killed or left by her, apart from the fact this cub was white...almost unnaturally so, as well as being well fed and wobbling about on strong little legs. It showed no fear of Challenger and allowed her to approach, going about its business and Challenger noticed the pale grey stripe on its head. So she picked it up and tracked it back where it came from.
Low and behold, Dys is there; sleeping in the evening sun with yet another cub; Challenger wakes her with a low cough.

Now, Challenger gets an explanation of what's happened and ends up giving the cub back almost immediately, thanks to the slightly manic look in Dys' eyes. But as annoyed as she is, she would never harm her best friends children and actually is very accepting of them, raising them as their second mother and helping name them.

Dys, Challenger, Hendrix and Vanu (c) sxmpra
credits for the cubs full designs will come once they're "old enough"
background provided by @/DragonRiderX16

[This piece was originally submitted on 8th Feb 2018 and started the Loss of Wife storyline idea]