New York City firefighter Scott Davidson died on 11 September, 2001 during the terrorist attacks on the Twin Towers in New York, and Pete has had his father's badge number, 8414, tattooed on his left forearm for some time.

Now, eagle-eyed fans of the No Tears Left to Cry singer have noticed new ink on her left foot, while she was out with her 24-year-old comedian fiance in New York.

According to Entertainment Tonight, the ink on Ariana's foot reads "8414".

The Saturday Night Live comedian was just seven when his father lost his life. Scott was last seen at the Marriott World Trade Center hotel after a second airplane hit the World Trade Center tower.

"It was sad how sad he was growing up," Pete's mother previously told the New York Times, explaining that the comic became a "lab rat" for those studying the effects of the attacks on the children of 9/11 victims.

Pete also confessed he ripped his hair out until he was bald and struggled with suicidal thoughts while coping with the tragic loss of his heroic father.

The comedian used to worry he was being hired just because he was a 9/11 victim's son. Now, he has learned to deal with his grief through his comedy and regularly includes the family tragedy in his stand-up routine.

"There's nothing I won't joke about, and I think it's because of what happened to me," Pete explained. "That's the worst thing that could ever happen to somebody. Now it's just like, 'Who cares, man?'"

But he has recently discovered some topics are off limits after coming under fire for a joke he made about the Manchester Arena bombing, which claimed the lives of 22 Ariana Grande fans last year (May17).

According to British tabloid the Mirror, the comedian joked about the tragedy during a stand-up routine at The Laugh Factory in Los Angeles in October (17), stating his future girlfriend must be bigger than Britney Spears, because "Britney Spears didn’t have a terrorist attack at her concert."

Charlotte Hodgson, whose 15-year-old daughter Olivia Campbell-Hardy was killed in the attack, told the newspaper, "For anyone to joke about this situation is disgusting and I think he should publicly apologise for it... We don’t need jokes about it, there have been plenty around, and it’s heartbreaking to hear every day. But for someone so famous to be doing it and now to be with Ariana, it’s outrageous. I think she would be horrified too."