Solomon's new form came as a surprise to everyone including Kang, who was quite surprised and satisfied with the fact that he reached S+. After a few minutes of chatting, Kang understood how he managed to pull it off and commended him for his courage.
The second elder didn't show anything on the surface but Solomon could easily sense a grudge from his behaviors. At the end of the day, he didn't blame him since he was the one who stole his serum.
As for Kang, he didn't care much as long as Solomon became useful to him. He didn't care much about the second elder, he let him be the council's leading figure as he always was.
What Kang wondered was whether he would get the full ten percent experience from the beasts or not and the fact whether Solomon was able to double his strength through the serum or not.
