As he sat, chained to the wall behind him, Zoro thought about when she first joined the crew, after all, she was the reason that he was stuck here.
...
Back then he hadn't trusted her at all, in fact, he had been sure that she was plotting something against them. She had just been their enemy back in Alabasta, and yet Luffy invited her into the crew. He knew his captain was a carefree guy, but Zoro had felt that this time Luffy may have been too trusting. Zoro decided that if no one else was going to, he would keep an eye on her, just to make sure she didn't do anything stupid. He had known that she was The Nico Robin after all, and not someone who should be underestimated. It was then she had come to speak to him. She had asked him if the crew was always as lively as she had just witnessed. After Zoro replied, " Yeah pretty much."
He was shocked by what he saw next.
She smiled at Zoro, and Zoro had thought he had just seen the most beautiful smile in all the world. One that would put the stars to shame. He quickly pushed that thought out of his head as he processed the fact that she was happy with the crazy Straw Hat crew. It surprised him that she, such a calm person, could be happy to see that the Straw Hats were just as chaotic of a crew all the time. As he looked at her once again he saw her staring at the waves. Her raven hair was blowing in the breeze and she looked happy. Zoro couldn't stop staring, for she was the most beautiful thing he had seen in all his life. The way she looked far off into the sea with those sky blue eyes, the way her hair blew softly in the breeze, He couldn't look away. She glanced over at him and saw him staring. She turned her head to look at him and smiled. That was the same smile that had made him fall in love, even if he hadn't known it then.
...
He sat, still chained to the wall. He remembered how stupid he had been back then. He had let his suspicion for her end up blocking out all the other feelings. If only he had trusted her back then, he might have had more time before ending up in a situation like this.
He looked around him, trying to get some bearings about where he was. The darkness surrounded him but he was able to use his Haki to get an idea of what was around him. It was stone. It seemed like he was in a cave. He called out to see if anyone was there, someone or something he might have missed. Nothing. He was all alone in wherever he was, and who ever had left him here had tied him up pretty well. His Katana were nowhere to be found. He couldn't even remember how he got here. All he knew was that he had to escape and find Robin, before it was too late.