The gaze of a tiny red dwarf burns more than the star itself could ever hope. Atmospheres stream away in cometary tails, and volatiles follow quickly. Mertidar is young- but it is just old enough to have ignited fully. It flares constantly, if more weakly- thus does a star so dim that it drops below visibility at distances that scarcely count as interstellar proclaim its fury.
Its closest daughter, Imratikura, is a boiled husk- its atmosphere, previously thick, burned away as Mertidar ignited; and the thin gases that seep up from its baked stone surface follow quickly. Further out is the lesson in planetary evolution that is Yadalemi; a world whose temperature dropped after ignition- the greenhouse atmosphere blasted away as the solar winds tore at it, and its remnants barely shield a surface strewn with the uncanny telltales of volcanism interrupted.
Third, then, is Abiodag- a super-earth, and the system's local beacon of hope. Abiodag struggles against the flares with a strong magnetic dynamo, and its high gravity makes it the first target of the stirred-up comets of the Outer Cloud as they spiral out to reach inner Mertidar system- those half-welcome visitors bring new volatiles as they strike it, slowly replacing an atmosphere that now consists mainly of what the comets bring. Its cooler nightside even nurses ice, and if its atmosphere stabilizes the planet may ultimately retain true seas.
The fourth world is cold, orbiting ten times further out than Earth's moon. The gravity of Mertidar, though, has already locked it to stare inward- the lopsided eyeball of Dulashke stares inward, barely retaining an atmosphere thick enough to distinguish sea from ice. Mertidar's last remaining planet, taking full years to circle on an orbit slightly stressed by the star's arrival in Arzharia system, hosts a number of moons larger worlds like Kizudea might find familiar- a set of icy planets, warmed by their parent's residual heat and their own orbits such that they reach temperatures far warmer than what miserly Mertidar could grant them.