Rin Ikeda
Rin watched the conversation between both of them, when she heard what the fish boy said she tried her best to not laugh. But he did have a point, he was human and had different facial features, and his body was also different from theirs too, she didn't notice that she started staring at him and observing his very movement. Until the moment that Dean told the fish boy that his face was weird too, that time she couldn't control herself and so she started to laugh really hard.
"Kyahahahaha! What kind of conversation is that?!" She said while laughing until she couldn't breath anymore.