The karina fruit is not poisonous for the giant race so they can consume it safely. They just forgot that other races cant consume it..
It’s poison for Kouichi but for the titans it’s just an sweet juice. And since he was the only ”not titan” person there, they probably didn’t think or know about it. And I think that Caius decision was right, it’s safer to stay in the titan castle with an doctor monitoring him than travel in that condition. Beside, he just need to take some medicine and prevent him to look at the moon to control those side effects, which is easy, you just need to close the window of their room during the night.
How do you know? Have I missed a panel?
Its explained on page 2 of chapter 12 and page 7 of chapter 13
You are super right, why did I miss the whole page? Maybe it didn't load when I read the chapter ( ・ω・ )
Alright, I need to ask this. First, why was that poison served on that party? And second, was he serously going to go abroad to look for the medicine leaving his sweetheart alone with those side efects???