"You have a sister."
Alan Doyle is the father of inmate Franky Doyle , who abandoned her when she was just a kid. He works as a plumber. He appears in season 1 when he tries to reconcile with Franky who instead rejects him, blaming him of having left her alone to face her life with her abusive mother.
He appears again in the first episode of season 4, when he peeks at his daughter who is out on parole, though his identity stays secret; it will be revealed in the following episode, when he runs after Franky two times letting her know that she has a three-year-old sister . Alan will introduce the two of them in a park.
In the episode 5x09, Franky convinces him to help her escape after he visits her in prison. He will use his plumber skills in order to pass escaping tools to her daughter after receiving the plumbing map of Wentworth from Franky inside a tennis ball.
In episode 6x03, after Franky's charges are dropped, he greets and comes back to his daughter in a park in a happy farewell scene.
Despite the negative past events, at present his personality seems to reflect a very comprehensive and positive father, who loves his daughters and would do anything for them.