In fact, even if you go back to the starting point and walk again, the ending will still be the same. The person has not changed, the mentality has not changed, the character has not changed, and the outcome will naturally not change. All thoughts of going back to the past are just comfort. M has never liked him, or even knew he existed. Over the years, he has just lived in his own obsession, watching himself act, and seeing that he deserves it.
Conception: