Grady and Mr. ____ return, and Mr. ____ tells Shug to leave the bed she's sharing with Celie (they have finished making love), so he can sleep with Celie, and Shug can sleep with Grady. As her visit to Celie's home continues, Shug begins encouraging Squeak to sing, saying that singing would do Squeak good, and build her confidence. Shug believes that Squeak's strange and interesting voice would be a hit at Harpo's bar.
Shug serves as the motivating force for Squeak's musical career. Shug has a talent for recognizing the talents of others. It is, of course, also Shug who recommends that Celie pursue her passion for fashion, and that Celie go on to expand this passion into a small business.
Harpo doesn't like the idea of Squeak singing, but Shug tells him it will be OK—she'll look after Squeak—and that Squeak's performances will bring in lots of money for the bar and for Harpo. This convinces Harpo to give Squeak's singing a try.
Although Harpo wants to control Squeak in a way he could not control Sofia, he wants money more, and therefore allows Squeak to perform at the bar.