Gamora just did what she could which, at this moment, meant sitting and watching. Nebula was, at least, eating food. That meant she could breathe a little easier. She wasn't talking, but Gamora hadn't expected that at first. Nebula, near as she could remember, had never been big on words or talking at all. Gamora had to wonder how much of that was Thanos, how much of that was Gamora herself? Was she truly seeing Nebula before all that? It certainly appeared that way. She wondered what she might learn, wondered what this might mean for them after it was...
Oh. She'd spoken. She'd asked Gamora a question and, for a moment Gamora actually appeared quite puzzled.
"I do not know." She went with being honest. "I was taken from my family when I was very young. You were the only person I knew for a very long time." She paused slightly, knowing she'd adjusted the story somewhat, but figuring it was better than hitting the child with another hard truth. "And the only friend I had for a very, very, long time. Until I met Peter and the Other Guardians, people who would one day become your friends too." She realized however that didn't entirely answer the question.
"I have not celebrated a birthday in a very long time. How old are you?"