Riff Bell is a singer/songwriter who is a close friend of Luke Wheeler.
He is introduced in the Season Four episode How Does It Feel to Be Free when Luke bumps into him after leaving a radio interview. Riff invites him over to his house for dinner and to catch up with his wife Heidi and his children. When they're alone, Luke asks him if he would like to be his opening act on his upcoming tour. Riff eventually accepts as long as his family can come with him.
However, during soundcheck Riff gets angry at his backing musicians and storms off. At Luke's insistence, he reluctantly takes to the stage to perform at the Beverly and goes down well with the audience.
His wife Heidi later turns up at Luke's office and informs him that Riff has gone missing. They discover that he has been admitted to hospital after being found in the company of prostitutes and under the influence of alcohol, something that Heidi says that she was aware of.