Little is known about Dermot's spotty past. On the surface, he and his associate Saint James are prospectors trying to make a living working salvage around New Vegas. They rent rooms at the Casa Madrid Apartments in Westside. The reality is that they are now actually slavers that abduct refugees from Aerotech Office Park and sell them to the Fiends for a profit. Dermot seems to be the more level-headed of the two, as he seems to be the one negotiating with the Fiends and is constantly forced to stop Saint James from molesting the girls, so as not to bring their price down. While staying at Casa Madrid, Dermot did not engage the services of any of the prostitutes there, unlike his partner.
On one particular case, Dermot and James had stolen a teddy bear from a little girl they kidnapped. Dermot bribed James with the bear as a means to keep his hands off the kids, as the Fiends want their goods fresh. The theft of the teddy bear has made Captain Parker suspicious.