Nathan Blake was the boyfriend of Ally Harrison and a solicitor at the law firm the pair both worked at. In September 2005, Ally introduced Nathan to her friends Lisa Hunter and Ben Davies. Nathan made a bad first impression, leading to the pair taking an immediate dislike to him. Nathan also rubbed Ally's brother Alex up the wrong way when dumping a high-profile custody case on Ally at the last minute. Not long afterwards, Nathan and Ally had a blazing row and split.
In October 2005, Nathan attended Dave's wedding, which Ally also attended. Nathan revealed that he had a fiancée, upsetting Ally. Regardless, Nathan later flirted with Lisa (who suspected Ben of having an affair with Ally) and the pair ended up sleeping together. When Ben decided to apply for custody of his estranged son Arthur, Nathan took on the case. However, Ben feared that Lisa's self-harming would be brought up in court and dropped the case to Nathan's anger.