Two for Joy by Louise Collins

Locked up in a maximum-security prison, Romeo’s highlight each week is a visit from Chad. Despite his friends, colleagues, and therapist all telling Chad to stop, he can’t, and he becomes the only joy in Romeo’s boring, bleak life.

More than his need to kill, he needs Chad to live, but a Copycat killer has other ideas.
At first flattered, Romeo relishes the new killer’s triumphs, but as he countdown his victims, Romeo realizes the danger Chad’s in, not only from the killer, but from his colleagues, and even more alarmingly, himself.

Romeo must do something drastic to reunite the Monster and the Magpie, but the Copycat is closing in on Chad fast, and he’s intent on doing the one thing Romeo couldn’t, concluding his countdown, and claiming number one…