Muzan Kibutsuji is the main antagonist in Demon Slayer. He's the one who turned Nezuko Kamado into a demon and was also responsible for slaughtering Tanjiro's family. He's the first of the demons and is easily over a thousand years old.
Along with exceptional longevity and power, Muzan has a twisted sense of affection. This makes it quite difficult to pick his favorites. Despite showing affection towards his lower demons on a frequent basis, he doesn't hesitate in killing them. However, there are a few who enjoy his special treatment.
Note: This article reflects the opinions of the writer.
Demon Slayer: Muzan's favorite demons
As mentioned before, there are a few demons who receive special treatment from Muzan. The infamous quartet is listed below:
Kokushibo stands at Upper Rank 1 in the Twelve Kibuki. He is the only demon to have a breathing style in the Demon Slayer series. In fact, Muzan views him as more of a business partner and one of his closest allies.
Thanks to this treatment, Kokushibo is extremely loyal to Kibutsuji and remains his strongest enforcer.
Akaza was also one of Muzan's favorite demons out of all his subordinates. The reason behind this is Akaza's extreme loyalty to his master. The Upper Rank Three demon was always sent away on special missions, something the Upper Rank 1 and 2 were often denied of. Muzan also tolerated his wish to not eat women, which incurred disdain from a few demons such as Doma.
Gyutaro is another one of Muzan's strongest bastions. However, he took a twisted approach to his dealings. Since Muzan favored Gyutaro so much, he chose to incorporate the latter's sister Daki as well.
The demon king believed that she was the only tool that could be used to control Gyutaro. However, he deemed Daki weak and believed she was the prime reason for her brother's death. His favoritism towards Gyutaro is further reflected in him allowing the siblings to share the Upper Rank 6 spot.
Rui is probably the youngest of all demons. Although his real age is still unknown, he is represented as a young boy in Demon Slayer. That said, Rui stood as Lower Rank 5 of the Twelve Kizuki. However, he lived up to Muzan's expectations and kept killing humans for sustenance.
Impressed by his loyalty, Muzan rewarded him with a special favor of starting a family. The Demon Lord was always against his subjects banding together as a team, but in Rui's case, he made an exception. Unsurprisingly, this led to the creation of the Spider Family. Notably. this favor wasn't extended to any other member of the Twelve Kizuki.
These four demons can arguably be dubbed Muzan's favorites in Demon Slayer. Overall, he is a very arrogant individual and doesn't really care about his followers. As much as Muzan loves to reward them for accomplishing tasks, he doesn't hesitate in killing them for failure.