For Bittner, her "twin intuition," was telling her that her brother was OK. Eventually, she and the others realized the truth: that he had died during the building collapse.
A Missing Half
Now, each twin grapples with the loss of the person they considered another half of themselves.
"He was my best friend, the person who helped make every decision I made," Bittner said, of her brother.
In dreams she sees her him and tries to call out to him, but he doesn't respond.
For Bittner, her brother's spirit does linger.
"What gets me through is I feel he's still here," said Bittner.
Bernstein says it was the first real loss he had suffered that didn't seem normal and that his brother was murdered.
"I'll see someone down the hall, that has a faint resemblance to Billy, and I think it's him," he said. "But realistically, I know it can't be him."
When Parkes said when she dreams about her brother she can barely discern him through a mist, but she knows he is there because he responds to her calls. Before he can say where he is, she wakes up. In her heart, he is still around.
"Every time I have a question, I can hear his answer in my head, I know what he'd say and how he'd laugh," she said. "I see the image in my mind's eye, and I constantly feel like he's inside."