why does grant go to the rainbow club after his solo visit with jefferson?

Grant has only been at the prison for thirty minutes, but not wanting the guards to infer that Jefferson is misbehaving, he stays for the rest of the hour and then leaves. By the time he leaves, Grant is frustrated with Jefferson and angry that he has been pressured into dealing with him by Tante Lou. Rather than returning to the quarter, Grant heads for the Rainbow Club to drink and relax. He also wants to see Vivian.