Poole was a reporter for the Rapture Tribune who was approached by Andrew Ryan to obtain information regarding Sofia Lamb's forming cult. By posing as a suppressed investigator, Poole gained membership among Lamb's cult and provided information to Ryan's goons. Eventually, Poole reported Lamb's attempts at garnering control of Rapture, resulting in her arrest. Following this, Poole was put in charge of Dionysus Park and carelessly threw parties. During this time, he sold two other notable individuals out to Ryan's forces. One was Eleanor Lamb under the fear that she would report his activities to her mother. The other was a deep-sea diver nicknamed "Johnny Topside" whom Poole admired but nevertheless turned in to Ryan who had assumed him a spy. This led to both Eleanor's transformation into a Little Sister and Topside into Subject Delta.
When Lamb escaped prison, Poole feared retribution and exploited a weakness in Dionysus Park's structure. With this, he drowned many witnesses to his actions and remained in charge. Following Ryan's death and Lamb's takeover of Rapture, he found himself stuck in a most unpleasant situation.
As Subject Delta progresses through Dionysus Park, he is prevented from getting ADAM for Lamb by Poole residing in a control station. Poole fears that acquiring the ADAM, which contains memories of its users, will expose his crimes. To force Delta to deal with the Little Sisters, Poole cuts off access to the Atlantic Express station until Delta meets his demands. Eventually, Delta complies.
Delta handles the Little Sisters and sees the events through the ADAM, exposing Poole's crimes. However, Lamb reveals over the intercom that she knew about Poole's actions all along and had considered Eleanor's transformation into a Little Sister to be a blessing in disguise. Lamb then opens the control booth and tells Delta about Poole's hand in his transformation into the Big Daddy. Thus, the player is given the option to either spare Poole or kill him. Delta's choice is later reflected in a Little Sister session wherein a statue of Delta either offers a hand of mercy to a begging Poole or strangles him with one vengeful hand. Should Poole be spared, it is unknown as to what happened to him after Delta leaves.