Prince Harry is a involved uncle.

In an interview with the Telegraph, printed days after the Jan. 10 launch of his tell-all memoir Spare, the Duke of Sussex mentioned he worries in regards to the different “spares” within the household. His brother Prince William, inheritor to the British throne, and spouse Kate Middleton are mother and father to Prince George, 9—who’s second-in-line, Princess Charlotte, 7, and Prince Louis, 4.

“Although William and I’ve talked about it a couple of times, and he has made it very clear to me that his youngsters will not be my duty, I nonetheless really feel a duty understanding that out of these three kids, no less than one will find yourself like me, the spare,” Harry informed the Telegraph within the Jan. 13 interview. “And that hurts, that worries me.”

The title of his memoir comes from the nickname bestowed upon him by the U.Okay. tabloid press and his household. Within the guide, Harry says he was “the shadow, the assist, the Plan B.”

He continues, “I used to be introduced into the world in case one thing occurred to Willy. I used to be summoned to supply backup, distraction, diversion and, if needed, a spare half. Kidney, maybe. Blood transfusion. Speck of bone marrow. This was all made explicitly clear to be from the beginning of life’s journey and frequently bolstered thereafter.”