I always wonder how Arias and Xenox would react if they lose one another to death.
Arias would probably kill whoever killed Xenox and become incredibly distanced again. He would be unrepairable.
Xenox would not comprehend Arias's death. He'll go for the rest of his life, talking to Arias like he's still alive even if he's not there anymore.
I think Xenox would be the saddest. He's a stupid dog.