I've Had Metroid Prime On The Brain

The thing I most want to know in the current volume of Captain Marvel is why the toxic planet of Torfa is toxic. It wasn't like that until a couple of centuries ago, but then it became a poisonous world, and that apparently hasn't faded in the time since then. It's also pretty clear that someone - Star-Lord's jerk father no doubt - is using those pirates to cut off the shipments of aid to the refugees there, so that they won't be as inclined (or able) to resist relocation.

My idea is something crash-landed on the planet back then. Not a meteorite that instantly exterminates everything in a flash of heat and concussive force, more gentle. Something that crashed somewhere secluded, then gradually leaked toxic substances into the planet. Something entirely undetectable, which makes it valuable. Think of it, a plague weapon that can't be found. All the aggressive space empires are gonna want that, and Marvel has a lot of aggressive space empires. Can't search for the source with all those pesky refugees around, so relocate them, under the auspice of compassion. Heck, you could even try and relocate them near a potential target, so the eventual sickness could be blamed on the poor refugees.

I'm curious as to what could cause the sickness, and how it can't be found or neutralized. Sounds like some sort of ancient, malevolent presence. Maybe some attempt by Ego the Living Planet to reproduce, or some weapon that's leftover from some long-past empire that had been floating for untold eons. Space is big, and the Kree, Skrulls, and Shi'ar weren't always the top of the heap. Hopefully whatever it is, it's something Carol could track down by a trip through perilous terrain and ultimately engage in a spectacular running battle, with lots of punching and energy blasts. Carol would make a pretty good Samus, even if she can't double-jump or curl into a ball and roll through small spaces.