Until he was 10 years old, Petro lived the life of an ordinary house cat.

He was a slim black tom with a white throat who belonged to a family on a street called First Place in Carroll Gardens, Brooklyn. Petro ate and stretched, played with stuffed animals, dozed in a beanbag chair.

When the couple had a second child, something changed.

“He was the baby,” said Petro’s owner Jennifer Chi. “He wasn’t getting enough attention anymore, and he was jealous.”

Petro began to seek attention elsewhere.

Everywhere else, in fact.

Upstairs to scratch on neighbors’ doors until they let him in, out the front window of his first-floor apartment and onto the sidewalk to demand pats and head-scratches from passers-by.