The narrator's anger and resentment are so clear - I expect the story is that the narrator tells us the story of his father, discovers something redeeming about his father, works through his resentment, and does something heroic in his own right.

I'm confused by one thing - you say "I don't even remember him," but you also say "I spent those years watching her evolve from a beatuiful young woman to a proper widow," as if the narrator was observing his parents marriage, which isn't consistent with not remembering his father.

I have to agree that it's hard to make much sense out of "to ensure that I could never compete with his memory, he is dead." Whether or not someone is dead doesn't affect the ability of anyone else to compete with that person's memory. The only thing that it affects is the memorialized's ability to personally gainsay the memorialization. But my feeling is that the rest of the opening is very sensible.

The picture I'm getting is that this kid grew up as the "beloved only son" of the "great hero/martyr", and his mother was the "devoted widow" of the same. Since he doesn't personally remember his father, and it would be truly despicable (and silly) for him to hate his father for choosing to save a large group of people (probably including his own wife and son) rather than himself, his resentment is probably more about how the adoration showered on his dead father prevented he and his mother from living a normal life.

Specifically, I'm guessing that his mother would ordinarilly have had the option of marrying someone who would have become a good father to Bran (the younger). But because she had to become an icon instead (and her son with her), Bran was denied a father for no sensible reason at all.

Making this scenario work requires two things, as I see it. First, that there really would have been someone that would have married Bran's mother and been a good father to him. It can't just be hypothetical. The best thing would be for this to be a specific person who would have married her and who Bran, in retrospect, wishes had married her.

The second thing is that Bran really suffered for not having a father. This is going to be very difficult on two counts. First, he did have a father, a great father who gave everything for his son. Second, if there were really some actual person that he knows and wishes had been married to his mother, then he should have had a pretty darn father figure in that person.

Arranging it so that both conditions hold true is the trick part, though by no means impossible. The key to fit this all together with Bran's resentment of the Atlantians is that something specific about the manner in which they idolized his father prevented him from being able to relate to both his actual father and a desired father figure. I can think of several alternatives.

The most sensible (though not supported by the text as it now exists) is that the possible father figure he desired was also being required to play a role as the "best friend" of the hero, one that meaninglessly prevented him from having any further association with Bran and his mother. For instance, if he were appointed to command some distant outpost to defend against the (neutralized) threat Bran's father gave his life to defeat. Or if the national honor demanded that he undertake some kind of suicide mission to avenge his friend's death.

Alternatively, it could be that Bran wished had become his step-father was simply unsuitable to marry so publicly revered a figure as Bran's mother, the "devoted widow of the great hero". This provides some difficulties, you have to present a character who we agree would have made a good father for Bran and a good husband for Bran's mother, but would still be totally socially unacceptable as a husband and father to the "devoted widow and son", such that he could not even associate with them.

Also, Bran has to be in a position to recognize that said person is the father he always wanted, despite the fact that they were kept apart. There are further tricks there, but by now I've probably over-explicated the potential story tree here.

I have lived in my father’s shadow my entire life. He is an icon: slayer of the [somebody], mage who kept Atlantis out of the sea. And to ensure ...