Even though, MC's brother did the torture but the sequel explains about his reasons. He wasn't swayed by the words of that filthy woman or succumbed under that tr*sh's order. The real reason was that - Prince had ordered MC's brother to torture him and he refused cause he firmly believed in his friend's innocence and kept insisting about the same but when he got to know that the Prince won't leave Jerd alive and won't be merciful to him he agreed to do that cause he knew that another man who was to be recruited by the bastard Prince were to torture Jerd, he would've been 10× more cruel and will likely will end his life because he was jealous of him as Jerd exceeded him in talent. Jerd will die as a man who was lustful and Cecelia whom Jerd requested him to protect will be also executed and they both will die an unreasonable death for the crime they haven't committed. Also he locked his sister so that she can't contact anyone cause apparently any woman who came into the radar of that that baron b*tch, she was either tortured, or got her engagement dissolved and sold in marriage to much older man, so just to show the b*tches that he's punishing her in order for them to not take any actions towards MC, he did that regretfully. MC's brother helped Cecelia and also Jerd was alive because of him, even though he indeed had to go through such thing. Jerd even insisted with Frederick (MC's bro) to kill him but he didn't complied with this wish of his friend, which Jerd was thankful of cause if not for that, he wouldn't have had gotten such a wonderful wife. Jerd was tortured physically while Frederick was tortured mentally. In the end all were happy, Cecelia married Frederick cause she wanted a man who won't betray her.