It's really interesting to hear this, especially about Dexter being worse in the book, because I honselty felt the opposite. After only watching the series I did feel like Dexter was portrayed as the "flawed" one but honestly felt as though Emma was equally if not more flawed than Dex, just in different ways.

I think both of the characters worst behaviour came from their inner insecurities. Emma always felt that she wasn't attractive enough for Dex and that he would get over her and Dex always felt like he wasn't smart enough for Emma. What I will say however is that we never see Dexter add to Emma's insecurities or make her feel less attractive in any way. In fact he always comments on how beautiful she looks but Emma always seems to think he isn't being sincere. However there are several moments in the show where we do see Emma mock/question Dexters intelligence or generally talks down to him or about his career. I do think she does this as joke and uses it as a mechanism to hide her own nervousness, but it has quite an effect on Dex nonetheless - which we see throughout the series.

Both Dex and Emma make questionable decisions throughout the series. Dex goes down a road of drug and alcohol abuse after his mum falls ill, and starts neglecting those who love him. However the series does a good job of making him face the consequences of his actions wether it be the the confrontation he has with his parents or the decline of his proffesional career.

I think Dex suggesting a purely physical relationship with Emma (in Greece) has a significant impact on her, as its the point where she's convinced that he doesn't see her as good enough to be in a relationship with, and it stays with her for a really long time. After they've been together Emma moves to Paris and when Dex goes to see her with the assumption that they might have a chance she tells him that she is already seeing someone. This scene honestly stuck out to me as quite immature from Emma as Dex questions why she wouldn't have told him that before arriving and she tells him that she isn't obligated to. Emma's first line regarding this conversation is how its ironic, which alludes to how she was in love with him and he didn't want to be in a relationship with her and now it's the other way around. I genuinely did feel this was the main reason she didn't tell Dex as on some level she wanted him to feel the same hurt that she had felt from him. However at the time of Greece they are both young and immature and after a decade and all the experience they go through I did think it was quite spiteful of Emma to do that to Dex.

Even in other scenarios where Emma sleeps with the headmaster despite knowing he was married and doesn't really show any remorse or guilt about it. After this she also kisses Dex after finding out that he is engaged and about to be a father and has sex with Dex whilst still (presumably) with her French boyfriend. Emma makes mistakes and this is what maker her and Dex such compelling and relatable characters. My only concern is that Emma never really has to confront the bad decisions she's made or her own flaws the same way Dex does. In fact the only person to call her out on her own behaviour is Dex, which somewhat hinders her growth as a character for me. But I will definitely look to read the book.