Malachy returns to Hollyoaks to find his father Eamon in July 2008. He and Kris make up and begin to build up their relationship. Malachy meets Mercedes McQueen. The pair begin a casual relationship and start to fall in love. Malachy and Kris go to donate blood and Kris is angered after he discovers he cannot give blood due to his sexual orientation. Later, Malachy gets results from the doctor, revealing he is HIV positive. Malachy is shocked and cannot come to terms with the diagnosis. Despite his condition, Malachy continues his relationship with Mercedes and involves in unprotected sex with her. Malachy leaves and turns to alcohol. During this time, Mercedes sleeps with Kris. Malachy returns and admits the truth to Kris, who realises he and Mercedes could now be infected. Mercedes is devastated and attacks Malachy. Malachy and Kris are horrified when they discover Eamon is dead and attack Darren Osborne for pretending Jack Osborne was Eamon in order to claim on life insurance.