"The Madness of King Scar" was a deleted song from The Lion King, which was to be sung to Nala by Scar, to the same tune as Scar's main song, "Be Prepared". After a short spoken interruption, it would be followed by the also scrapped "Be Prepared" reprise. The song was completely rewritten for the The Lion King musical and is now sung/spoken by Scar, Shenzi, Banzai, Ed, Zazu, and Nala.
In the deleted movie version, King Scar, in his delusions of power, wonders why he is not loved by the Pride, and asks Zazu what Mufasa has that he doesn't. When Zazu does (notably mentioning "respect of your species, a loving family, a devoted queen"), Scar is struck by the last suggestion (a queen), and tries to seduce Nala into becoming his queen with this song, in spite of Nala's attempts to explain to him how the Pride Lands are going to rot because of his incompetent leadership. As he comes dangerously close to her, she scratches him across his face to drive him away. Scar then comes out and try to marry her by force in front of the other lionesses. However, Nala refuses and is called to exile as punishment; the Lionesses' support of Nala lead him to call in the Hyenas, resulting in the "Be Prepared" reprise in which Nala is banished from the Pridelands.
In the musical version, King Scar worries about not being favored among the Pridelanders while dealing with the problems mentioned by the hyenas and Nal. On top of that, Scar is driven mad by the delusions he has of Mufasa's ghost. To calm his mental illness, Zazu suggests Scar gets a queen which leads Scar to choose Nala, who precisely comes in Scar's cave at that moment to try and convince him to actually do something about the problems going on that only he can fix. Not listening to her demands, he tries to seduce her in song, and she scratches him across the face as an act of refusal. Scar threatens Nala by claiming that one way or another, she will be his, resulting in her leaving the cave as he declares that Nala and the pride will be completely his no matter what.