First of all, a question: was Colin in love with Rafael from the beginning? Because, in the end, when reporting the moment he fell in love, the author refers to a scene that he said belonged previously to Rafael, that is, the smile would be Rafael's and not Gabriel's ( http://www.mangago.me/read-manga/one_step_from_the_end/nmt/iur_chapter-73/pg-6/), in fact, in my opinion, Rafael's expression is one of shock and not of surprise or any other feeling, as if he had discovered at that moment that Collin was in love with him from the beginning ... so, in the end, despite my criticisms to follow, I think the author ended the story with the couple he wanted and that's it.
Regarding the second story, I think it's important to consider that Gabriel's dual personality stems from the stress caused by his personal relationships with his parents and Colin. So, although I particularly preferred Rafael’s personality, I didn’t like the ending, because, as I said above, Gabriel’s double personality was also caused by the fact that Colin always takes his family frustrations out of their relationship, possibly Collin didn’t know his participation in this disorder, after all, he was also a problematic child (he had no family structure - his father is an idiot, totally inhuman). However, throughout history, he discovered that it was one of the causes of Gabriel's double personality, but instead of helping with treatment, he preferred to continue his revenge (I think here the "devil's" wish would have been fulfilled, after all, unlike the first story, this one had a concrete "victim"; in fact, the initial desire to erase Gabriel's memories would have been better, because then Colin, who was the holder of the "diabolical book", would be the most affected, after all he would not be happy to be forgotten by Gabriel/Rafael, this fact is confirmed by the false aminesia, that is, instead of Colin continuing his life and forgetting all the abuses suffered, he also decided to have an aminesia and give a second chance to the romance between them, and at the same time, this ending would end with all lies and manipulation). Thus, I think that the author treated the double personality superficially, that is, in my opinion, not showing the real consequences of the double personality in the lives of the characters, but merely citing them superficially, it opened margins for interpretations favorable or not to some characters (was it intentional?), besides leaving some holes and, finally, to finish the story, he chose to sacrifice one of the personalities to the "devil", in order to quickly finish a complex aspect of the story, but, unsatisfactory (again, in the my opinion), since Gabriel had a tragic and undeserved end, considering all the suffering he also went through. In other words, in my opinion, the author could have ended up with one of the personalities, but through clinical treatment, so that Gabriel/Rafael could solve his problems, just as Colin could participate in this process and have his problems solved too, and that would put an end to all manipulation and lying in the relationship between Colin and Rafael/Gabriel.
THE COMMENT CONTAINS SPOILET
First of all, a question: was Colin in love with Rafael from the beginning? Because, in the end, when reporting the moment he fell in love, the author refers to a scene that he said belonged previously to Rafael, that is, the smile would be Rafael's and not Gabriel's ( http://www.mangago.me/read-manga/one_step_from_the_end/nmt/iur_chapter-73/pg-6/), in fact, in my opinion, Rafael's expression is one of shock and not of surprise or any other feeling, as if he had discovered at that moment that Collin was in love with him from the beginning ... so, in the end, despite my criticisms to follow, I think the author ended the story with the couple he wanted and that's it.
Regarding the second story, I think it's important to consider that Gabriel's dual personality stems from the stress caused by his personal relationships with his parents and Colin.
So, although I particularly preferred Rafael’s personality, I didn’t like the ending, because, as I said above, Gabriel’s double personality was also caused by the fact that Colin always takes his family frustrations out of their relationship, possibly Collin didn’t know his participation in this disorder, after all, he was also a problematic child (he had no family structure - his father is an idiot, totally inhuman).
However, throughout history, he discovered that it was one of the causes of Gabriel's double personality, but instead of helping with treatment, he preferred to continue his revenge (I think here the "devil's" wish would have been fulfilled, after all, unlike the first story, this one had a concrete "victim"; in fact, the initial desire to erase Gabriel's memories would have been better, because then Colin, who was the holder of the "diabolical book", would be the most affected, after all he would not be happy to be forgotten by Gabriel/Rafael, this fact is confirmed by the false aminesia, that is, instead of Colin continuing his life and forgetting all the abuses suffered, he also decided to have an aminesia and give a second chance to the romance between them, and at the same time, this ending would end with all lies and manipulation).
Thus, I think that the author treated the double personality superficially, that is, in my opinion, not showing the real consequences of the double personality in the lives of the characters, but merely citing them superficially, it opened margins for interpretations favorable or not to some characters (was it intentional?), besides leaving some holes and, finally, to finish the story, he chose to sacrifice one of the personalities to the "devil", in order to quickly finish a complex aspect of the story, but, unsatisfactory (again, in the my opinion), since Gabriel had a tragic and undeserved end, considering all the suffering he also went through.
In other words, in my opinion, the author could have ended up with one of the personalities, but through clinical treatment, so that Gabriel/Rafael could solve his problems, just as Colin could participate in this process and have his problems solved too, and that would put an end to all manipulation and lying in the relationship between Colin and Rafael/Gabriel.