I think those are editor's suggestions/corrections. [] and () seem like parts added and parts to be taken out, respectively.
Noah looked at Yoohyun in disdain and raised his chopsticks. He used them well(,)[.] (and) I thought they would become closer like Peace [did] if they went in dungeons together. Well, they might not like each other as their [compatibility] (synastry) was not good, Noah's being poison and Yoohyun's being fire.
Fantasy · LeeOn
I'm enjoying reading this story a lot, but I wish things like skill names would stay consistent throughout the whole story. I kinda wish the name orders would go back to the way it used to be at the beginning, too.The contract the jellyfish offered doesn't seem optimal. And I think it's funny that all the new baby monsters that come into Yoojin's care go through being put in their places by their older siblings, so to speak.
ch 154 S Classes that I Raised 154 I Was Assigned (4)
The S Classes That I Raised ( The S Classes monsters that I raised)
Fantasy · LeeOn