It isn't the mark that he's talking about making her different. It's the things she says, the things she does. The way she presents herself and the honesty he can see flowing in everything that she is. He isn't falling for the Herald, some symbol of Andraste or whatever other bullshit they want to throw out. He's falling for the woman. Ginevra Trevelyan.

"The fact that you've said as much, that you've put thought to it at all, means you're leagues ahead of any of the other rebels," he says quietly. "No one really knows where that line is. The fact that you're constantly looking for it, that you haven't given in, means it'll be that much harder for you to become like the others. That much easier for you to keep yourself as you are."

That much harder for him to stop loving her.