Kisora knew that Green wasn't an existence that should exist and he along with thousands of eggs that the experiment he had allowed them to previously do on him had produced were meant to die.
It was at a time when he was desperate not to be the last of his kind and now seeing Green in front of him, and smelling him, he could tell that he was a dragon which made him want to kill him the more since Green reminded him of a time when he was weak.
This was why when Kisora had told Green his name, he had not been expecting much of a reaction or anything at all, which was more surprising for Kisora when he got one that he wasn't expecting.
"Ki…Kisora?" Green asked with mild shock on his face, an expression that slowly made way for a big smile to appear on his face as he stared at Kisora's face with twinkling eyes that in no way hid the happiness he felt.