William Brentlinger was supposed to be still-born, but the boy and his twin, Reagan, came into the world on Dec. 17. William lived only 11 days, but a photographer captured images of the siblings together in their first days.

Parents Lyndsay and Matthew Brentlinger, of Northwood, Ohio, said they found out at 23 weeks that William would be still-born, 13abc reported.

"With twins you have frequent ultrasounds," Lyndsay told the news channel. "They said we just see something abnormal with the heart and sent me to maternal fetal medicine."

Lyndsay said the left side of his heart wasn’t functioning when he was born, and “he just had a bunch of abnormalities.”

A family friend contacted professional photographer Lindsey Brown, who squeezed in a newborn session at the family’s home during the holiday rush, as the family did not know how long William would live.

“Other than that, it wasn’t abnormal at all, as William acted like a completely healthy baby boy,” Brown told FoxNews.com by email. “The parents were extremely strong and held it together.”

Brown told FoxNews.com that William and Reagan’s mom and dad were open about their son’s struggle and treated both babies like nothing was wrong.

“After they grew side by side, they only really know one another,” she told FoxNews.com. “I often wonder if little Reagan feels like something is different now. Breaks my heart! But I’m so happy the parents will have these photos forever and to share with Reagan and tell her all about her big brother.”

For the Brentlingers, capturing the brief moment when their twins were together was priceless.

"They are beautiful, and he is beautiful,” Lyndsay told 13abc. “In some of them, you can see he is wide awake with his big beautiful eyes. It's something we will definitely cherish."