Responses
Yeah, honorifics are hard to translate. If you translate them, it sounds bizarre in English. If you leave them out then the text loses something ... Personally I wish people would go for the middle ground... Leave them in but don't try translating them... Having them constantly say Nii-san would be better than having then say older brother, older brother, all the time.
A little bit weird that they call each other big/little brother.