Although there are two habitable planets in this solar system, the only life that is sentient is actually found on the star they orbit. Its surface is alive with regular flares of magnetic and coronal activity, where strange supernatural life has emerged on its own in the plasma plains of the surface.
As commonly happens with supernatural beings, these fire beings living in the sun possess a humanoid form. They are not only immune to extreme temperatures and the vacuum of space, they can also fly between planets at will. Their travel is, however, always slower than light speed.
When they come planet-side to go sightseeing of the exotic non-burning environments of a terrestrial world, they usually visit places full of life. They avoid barren deserts and cold places and oceans, so grasslands, jungles, and forests are or particular interest to them.
Predictably when beings of the sun touch down in a forest, fires erupt. While such destruction amuses them for a while, they eventually grow bored of the conflagrations, as their home star’s environs are naturally alight, and they came to see a world that was something else. With their mastery over fire they extinguish the flames, leaving burned sections of forests in their wake. Thus, every couple years, when boredom sets in, rotating numbers of sun-dwellers visit the planets, resulting in continuous burning of the plant matter in the worlds.
(I do not own the images in the above collage, and all copyrights belong to their respective owners.)
Go to another world …