References to Dougal's family are rare. In "Grant Unto Him Eternal Rest", he mentions that his parents are dead, and also refers to an uncle who died after his heart stopped beating for a week. It is unclear how Dougal entered the priesthood, with Ted wondering, "Dougal, how did you get into the Church? Was it, like, collect twelve crisp packets and become a priest?"
Dougal is dim-witted and childlike. In "Chirpy Burpy Cheap Sheep", it is revealed that Ted has made him write a list of things that do not exist, which is on a pull-down chart in their bedroom. Often he says things that Ted specifically told him not to say, such as by asking about Bishop Brennan's son, as well as shouting to Ted to ask if the Bishop found a large number of rabbits that they are hiding in the parochial house (fortunately for Ted, the bishop was more concerned about Dougal addressing him by his first name instead of using his proper title). In "The Mainland", he forgets to have any breakfast and fails to realise this until he and Ted are waiting for Father Jack at the optician. He also nearly gives a visiting bishop a heart attack when he screams in excitement after remembering the director's cut of Aliens is airing on television that night.
Sometimes he talks more sense, however, such as when Ted inadvertently winds up his unravelled jumper upon discovering that it could provide a way out, and he asks what use it will be when all wound up. In "Kicking Bishop Brennan Up the Arse", he suggests that Ted use his fear of Bishop Brennan to his advantage to carry out the forfeit he was assigned by his rival, and to get Bishop Brennan into position, draws a crude watercolour painting on the skirting board, depicting a man wearing a bishop's hat.
By the time the show begins, Dougal has been exiled to Craggy Island as punishment for unknown misdeeds. In an early interview, the writers stated that it involved "a baptism gone wrong". In "The Passion of Saint Tibulus", Bishop Brennan says that Dougal cannot be allowed back into "the real world" after "the Blackrock incident", in which hundreds of nuns' lives were "irreparably damaged".
In "A Christmassy Ted", Dougal performs a funeral that Ted was meant to do, but forgot about. Ted is alarmed to learn from Mrs Doyle that Dougal is performing a funeral, and the consequences of Dougal performing the funeral are predictably disastrous.
Bishop Brennan despises Dougal, at one point referring to him as a "cabbage". He also does not take kindly to Dougal calling him "Len", often shouting profanity at him when he does.
Dougal is famously known for wearing an Irish football jersey when he is in bed. He and Ted share a bedroom, but owing to his childlike nature Dougal does not sleep with a normal blanket like Ted; instead he sleeps with a child's cartoon character bedspread (specifically Masters of the Universe).