"DRINK! FECK! ARSE! GIRLS!" - Father Jack's catchphrase.
"How did that gobshite get on the television?!"
Father Jack is a surly, rude, alcoholic, lecherous, senile, foul-mouthed and violent priest, who frequently lapses into aggressive behavior, especially when his fellow clergy deny him alcohol (which he refers to as "drink"). Jack makes no attempt to mask his contempt for his fellow clergy and pretty much anyone else he encounters. He rarely speaks in a coherent manner (possibly a result of his constant drunkenness) and often shouts out a series of random words: "Drink! Feck! Arse! Girls!" sometimes accompanied by convenient hearing difficulties making him shout "What!" He occasionally has outbursts including "Knickers" and "Women's knickers". He is the first priest to denounce the Beatles, as he knew what they were up to.
In the past, he taught in a Catholic school in St Columba's and was notorious for being brutal as he once beat up a student with a shovel. His unpleasant method caused one of his students, Father Jimmy Ranable, to become a serial killer in a massacre. He was sent to the Craggy Island parochial house after a disastrous wedding in Athlone of which he has fond memories. Jack spends most of the day sitting in an old armchair in the parish house sitting room. He is often found drinking, sleeping, shouting out profane obscenities or acting rudely to other people in the room. Father Ted Crilly, Father Dougal McGuire and Mrs. Doyle are shown to be generally tolerant of his drunken antics. Graham Linehan, one of the creators of the show has stated that Father Jack is the grandfatherly element of the show. Despite being one of the main characters, Jack generally displayed a more antagonistic role than Ted and Dougal.
Jack's drinking is not limited to alcohol, as he will drink any type of liquid he can get his hands on (minus water which he despises). This has brought him trouble many times. Twice, Jack has drunk Toilet Duck (bleach) which has made him hallucinate, seeing pink elephants and the people around him as bizarre oddities. Jack also drank floor polish that slowed down his metabolism, convincing everyone he was dead. It was a couple of days before the effects wore off him. Jack has also had trouble from drinking Windolene at some point. One year, Ted tried to make Jack give up alcohol for Lent. After a day and a half without drinking, the effects of his alcoholism wore off him. However, when Mrs. Doyle returned from her Lenten pilgrimage, she found Jack sucking through tubes connected to bottles of wine hanging from the ceiling. Jack is constantly inebriated and is often completely oblivious to the people and situations around him, unless they interfere with his daily routine of drunkenness and sleeping. Despite his drunkenness and senility (and possible mental deterioration, brought on by alcohol), Jack is shown to have carried out careful plans such as hitting Ted with a car and placing a spider in his mouth, and had sense enough to escape a bad situation when the other priests were debating about it.
As well as being alcoholic, Jack also has poor personal hygiene, shown with a ring of scabs around his mouth, unkempt hair, stains down his clerical collar and smock and decaying teeth. Ted once panicked because he believed it was the time of year for Jack's bath. Jack also has a variety of foul smelling odours such as vegetables and also fur, which made him a magnet for hundreds of rabbits. When Mrs. Doyle cuts Jack's nails she wears a helmet, as does everyone else in the room. When Jack was provoked by Father Jessup, he locked him in his underpants hamper, where he was tormented by the smell. Jack sometimes sleepwalks naked which has constantly attracted the unwanted attention of Bishop Brennan. Jack also seems to suffer from blindness in his left eye, due to its milky white appearance. Jack's overall appearance and hygiene generally got worse as the series went on.
The other residents of the parochial house are all used to Father Jack. Dougal regularly brings Jack outside, although the latter has to be put in a wheelchair as he is impossible to convince to leave his armchair. Mrs. Doyle treats Jack with affection despite his rudeness and brings him tea, even though he hates it. However, Jack can sometimes be too much. Ted cheered up when he learned that Jack would have to be sent to St. Clabberts Old Priests' Home. He hates doing confession - partly attributed to his fear of enclosed spaces - and regards the sick and poor with contempt, referring to the needy as a "shower of bastards". It is later revealed that, according to his will, he has saved up £500,000. Ted partly attributes this to Jack's "never giving money to charity" and the fact that "he wouldn't wear trousers during the summer". This result in Ted and Dougal purposely went out to buy lots of floor polish, hoping that Jack would find and drink them and die, knowing they would inherited half a million pounds between them from his will.
Jack is often extremely aggressive and violent, frequently lashing out at Ted and (occasionally) Dougal, with Ted being the most subjected to his drunken violence as well as other characters. Jack's violent behaviour and horrid attitude may be caused by his constant alcohol consumption, though it was shown in several flashbacks that Jack was already quite aggressive when sober. Jack's alcoholism may also cause him to suffer from diplopia (double vision), as he asks Ted "where are the other two" when he sobers up in one instance. Jack also is prone to deafness (due to a occasional build up of wax in his ears). However, it may simply be him not bothering to listen, as he is seen to hear fine when he is offered brandy.
Jack generally spends most of his time sitting, sleeping or passed out in his armchair, though he does occasionally venture from it. It is somewhat inferred in the episode "Cigarettes and Alcohol and Rollerblading" that Jack's alcoholism may stem from his banishment to Craggy Island.
- When cleaned up, Jack looks like a kind, caring gentleman.
- Ted stated that he is a "traditionalist" who disapproves of "a lot of the modern thinking within the church". This fact shows when he preached to children in a Catholic school and told them that they were going to burn for eternity in Hell.
- He has a fear of being buried alive, so he doesn't go into confessionals with their enclosed spaces (and he doesn't really want to take confessions). He also has a fear of doctors, for they remind him of his mortality, so he avoids the sick (as well as the poor and the needy, and calls the latter a "shower of bastards"). These are only surpassed by a fear of nuns which could be due to their abstinence from sexual activity since Jack is seen several times to enjoy objectifying women.
- Dougal thinks that Jack once had a trial with Liverpool F.C. but Ted corrects him, saying he was on trial in Liverpool. Why this was remains a mystery.
- Due to his fondness for drink, he can identify any type just by the clinking of the bottles, as displayed in the episode "Old Grey Whistle Theft"; he also has the ability to empty two bottles of spirits faster than anyone can perceive. Furthermore, he speaks in more polite and calm voice when someone offers him drinks, as seen in "Tentacles of Doom".
- The reason for his extreme alcoholism may come from the fact that he was exiled to Craggy Island as he sadly expresses to be still on that feckin' island when he is sober. This is unknown. However, Jack may have been an alcoholic before, which could explain why he was sent to Craggy Island in the first place. His alcoholism could have brought on his sadistic personality, resulting in the events at the wedding in Athlone.
- He has massive earwax and head wax built-up, which Ted and Dougal often mine from him to access an indefinite supply of candles. Ted stated that he and Dougal need a syringe to extract the wax.
- The tune that will make him stand up is the French national anthem "La Marseillaise".