I've been craving this idea for some time, and would really like to play it out if anyone is interested. Please, PM me instead of replying to this thread.
Below is the summary of the idea:
From birth, he had been trained to be an assassin. By the time he was twelve he was already being sent on missions by himself, and was quickly making a name for himself as one of the most deadly and talented killers there was. By the time he turned eighteen, he was at the top of his game. His identity had long-since been erased, and he never left a trace of evidence behind when he did a job.
That all changed when he was given the last job he would ever take. It seemed simple enough, kill everyone at the address he was given. The pay was extremely generous, all up front - and his rates weren't exactly cheap to begin with. He entered the large manor and dispatched of the man and woman he found there, but wasn't quite prepared for the four-year-old girl he found sleeping in her room. The sight of the girl and the thought of what he had just done to her parents made something snap inside of him. He whisked the girl away, burning the house down to cover up her escape. He found a noble family to take care of the girl, a man and woman who couldn't have children of their own.
He accepted contracts very rarely after that day, spending all of his free time watching over the girl, watching her from the shadows as she grew up and keeping her safe. But when she came of age, she began to grow more and more curious and suspicious about some of the oddities of her life; about why she didn't look much like her parents, about the figure that she occasionally glimpsed in the shadows out of the corner of her eye. About the time the men who threatened her on the street at night appeared to have dropped dead of their own accord.
Okay, so there are a few different ways I see this being taken.
One way was that, I was thinking that maybe she sees him at some point, she follows him and they eventually meet. She would ask him things about why he is protecting her and such. This idea would need to be developed more.
The second way that this could go is that he decides to make her his bride. This is a loosely set historical story (although that can be up for debate) so marrying a man who is close to double her age isn't anything new. Again, this would have to be discussed.
If you have another way that this could play out, let me know. But please, PM me. Thanks :)