Hearing what Emily had just said, Roger was forced to relent for Emily's safety. Because what Emily had just said, was true as it was.
It was more likely that Emily would be found soon if she was with Roger. But if Emily is not with Roger, there are still many opportunities for Emily to lose from being hunted by the hunting team.
Moreover, with Nicholas not killing Alfred directly, surely the old man would not remain silent, after getting an attack from Nicholas, Alfred will certainly take revenge more cruelly than before.
After thinking of an appropriate answer for his little sister, Roger then lifted his chin and looked at Emily who was in front of him.
The look Roger gave Emily was a look so deep, a great hope etched from the look in his eyes for Emily.
Roger took a deep breath, then let it out slowly. It was as if with every breath he took, Roger was ready to let his little sister go.