I went back and looked but it says Arnold's ear were ripped off before he became a slave. Don't know if that means they were ripped off to be sold or if something happened before he became a slave. I'm assuming the ladder considering his sister is also missing her ears. Mainly because the manga shows other beastkin slaves and they still have their ears. (ch 6 btw)
So... "you are allies after all" since when do "allies" try to kill you and your friends and enslave the entire race you are allied/friends with?? Seems like enemy behavior to me tbh or are we just supposed to forget they (old man and the kid) wanted and specifically asked the king to help do said horrible things?