I've just read A Street Cat Named Bob by James Bowen. It tells of how a stray ginger Tom cat, quite literally, saved the life of recovering heroin addict living in sheltered accommodation in north London.
James Bowen's story begins when he first met Bob at a bad time in both their lives - including when they would busk together in Covent Garden, ride London buses & shared a flat - and is told in such a way that it's never mawkish; the redemptive qualities of their relationship comes off the pages very subtly. The book never shies away from the utter desperation and helplessness of a recovering drug addict but demonstrates that by putting purpose, and something to live for, back in your life can be the lifeline you need; you've just got to reach out for it when someone throws it at you.