In reality, Ren Xiaosu did not mean to slap Luo Lan's forehead. His intention was just to open a Shadow Door next to Luo Lan and pull him to a stop. After all, they had a good relationship going. Moreover, Ren Xiaosu also felt a vague sense of respect for Luo Lan and his soldiers. Even though he wanted to save Xu Xianchu, Ren Xiaosu did not want to cause them too much trouble.
It was purely just a slip of the hand that he slapped Luo Lan's forehead. It was because he still didn't have full control of the Shadow Door.
However, it was wonderful that it made Luo Lan think it was Luo Xinyu who did it. This girl and Yang Xiaojin had already sabotaged him so many times in the past. If Ren Xiaosu could make the Qing Consortium pay more attention to them, he really would not mind slapping Luo Lan's forehead a few more times.