Three Is None
There were little things, here and there. Like the fact that Severus and Ginny shared a bedroom, while Harry had a separated bedroom in the attic. Yes, he always slept in the couple's bed, and he liked to have his own bedroom. More than that: he understood he had to have a bedroom, so that people wouldn't think he slept with the couple. And yet... that was one of the little things that would make Harry wonder.
Another little thing was that the house was theirs. They had planned and decorated it.
And last, but not least, Julia was Harry's goddaughter, not his daughter. When there was a disagreement regarding her upbringing, Harry had to keep quiet. Severus was stubborn and uncompromising about everything concerning his daughter, and didn't condone any breach of the rules or behaviour he expected from Harry in this respect. A mere chocolate frog given at a bad time could trigger a storm.
The truth was that Harry was an outsider who had joined an established family. Yes, he had been integrated to the family, but deep inside he knew he would never really be "one of them".
Harry loved each one of them in a special way, so he had never complained. That evening, though, when he arrived from Hogwarts, Severus and Ginny had news for him.
"Severus and I have been talking," said Ginny. "Julia's almost two years-old now, and 'The Simmering Cauldron' is doing well. So, we think the timing is perfect to have another child."
Harry started, and his own reaction surprised him: he felt sad and hurt. Ginny kept on talking, but he didn't listen. Suddenly, he realised she was staring at him with a frightened look.
"I'm sorry. I'm not feeling very well. I'll go to my bedroom," he said.
In his bedroom in the attic, Harry pondered on the situation. He had arrived at a limit. He wasn't really part of the family. And he wanted to be part of a family. He wanted to have children, his children. He loved Ginny and Severus, but the sad truth was that he would have to break with them and build his own life.
Ptyx, October 2006