Well I know Ian is Brian, but I consider them different people, since they've experienced different things and have lived different lives. But even if Ian does get Brian's memories and their personalities mix or if Ian gets the memories back but stays as he is now. The fact that the ml likes Brian the person now and isn't really ever going to like Ian the person, is what gets me. And I think the ml only really loves Brian, and may somewhat have fond feelings for Ian.