There are many ways in the story "The Half Brothers" that the author, Elizabeth Gaskell, develops her themes of loyalty and self sacrifice. One of these is that we never actually find out the first name of the narrator, which emphasises that the story is more about the narrator's brother than him. This shows that the narrator is telling us that his brother is the more important issue ins this story than he himself, which shows how loyal he is to his brother. .
The aunt in this story, Aunt Fanny, gives her whole life to both her sister and her sister's children, which definitely shows great loyalty and self-sacrifice as she is giving her life to helping her family, which is extremely loyal and also a sacrifice. We know of her loyalty as the narrator says of Aunt Fanny "she was a kind, warm-hearted creature, who thought more of her sister's welfare than she did of her own" and goes on to say that "it was on her bit of money that they principally lived". .
There is a contrast in this story to "The Unexpected", where the woman does not stay with the man who is very ill, whereas here the person suffering does not have to suffer alone, and we feel that there is something 'romantic' about sacrifice for love. Aunt Fanny does not abandon the person suffering here in "The Half Brothers" as happens in "The Unexpected", so she is showing she is far more loyal and more willing to make sacrifices. The story is essentially about brotherhood and sacrifice, and it praises loyalty and sacrifice as Gregory becomes like a saint. .
The story also suggests Mrs Gaskell's own view on loyalty and self-sacrifice, that she is very encouraging of it and recognises that it is important in life. As well as this, the story hints at religion in certain ways, particularly with the narrator saying that his father's last words were "God forgive my hardness of heart towards the fatherless child" - although this could also be just an expression.