My husband's first wife died when their son was four. I didn't know him at the time. We met for the first time a little over a year after her death and he was pretty upfront that he was a very involved single dad. In many ways I fell in love with his son at the same time I was falling in love with him. Had I not I doubt we would have married when we did because I don't see him marrying a woman who hadn't come to love his child. However, I have always considered M my stepson [and often referred to him as E's son] because I acknowledge that he had a mother who loved him and his father very much and would be with them if things were different. But things aren't different. I love them both and I love the family we have built now.
While M will always be my stepson I have always considered him the brother [halves sound wrong and silly] of our five daughters [one of whom died way too soon, one of whom is still in utero, and one of whom joined our family as a foster child]. I have appreciated and often praised the amazing big brother he has always been to them. He really has and they are very fortunate to have him in their lives.