Jing Yiran refused to learn. Jing Yichen beat him to a pulp, every time they had a scuffle, but he never stopped provoking Jing Yichen. Jing Yiran would end up saying something or the other that ticked Jing Yichen off and he wouldn't hesitate to shower him with punches, in return.
Jing Yiran knew the bottomline. Jing Yichen would not kill him, because they belonged to the same family.
Jing Yiran had never been able to beat Jing Yichen, since they were kids. Jing Yichen was always stronger and swifter than his little brother. Jing Yiran was used to this, so much so that he didn't mind being beaten up as long as he was able to annoy Yichen. As long as Jing Yiran was alive, this was his motive – to annoy Jing Yichen and make life difficult for him.
Most times Jing Yichen was unaffected by Jing Yiran's childish behaviour, but at times Yichen would get so instigated that he would want to kill someone.