Makemake was discovered in 2005. It was a target of NASA's Kuiper Belt Exploration Program (KBEP) and was first visited in 2071. It was shortly colonised after. It is considered impossible to terraform due to it's extreme cold, and as such there are not many inhabitants. It's moon was never cared for, due to it's extremely small size.
The planet has multiple colonies all across it. The people never go outside, as the radiation would basically kill them due to there being no atmosphere and the cold. They live in airlocked buildings, sort of like early martian colonies by SpaceX.
MK 2 is MakeMake's single moon. It is incredibly small. The moon is tidally locked to MakeMake, similar to Luna before terraforming, however this doesn't effect the moon itself much. It has no inhabitants, as there is basically no reason to live there, and no real way to land safely.