Sebastian was uncomfortable at best, his gaze continually moving around the crowded ballroom. The sniper wasn't used to this kind of setting, to not having to constantly hide who he is when surrounded by London's finest, but his daughter had arranged it for today only, a temporary moment of peace for the happy pair dancing the night away. Jim looked at ease, an easy smile on his lips as his obsidian eyes dart from face to face of the people surrounding them. At least he was comfortable, though that may have something to do with the fact that he was able to torment his enemy without saying a word.
Sebastian's cool gaze moves from the face of his husband to the smiling face of his daughter. Thalia looked truly beautiful today, dressed in a pale peach dress that swirled around her legs whenever young Hamish twirled her around. She was happy, happier than Sebastian has ever seen her, and that's what makes all of this hassle worth it. He looks at Hamish next, finding the same happiness burning brightly in the young man's eyes, eyes so like Sherlock's that it was almost too strange for words. Hamish's hair is a shade lighter, but that was the only thing that really resembled his mother.
Irene Adler sat at a table across the room, sending sly smirks in Sherlock's direction that Sherlock easily ignored as he watched the dancing couple intently. His husband, however, had eyes only for Sebastian and Jim. He didn't trust them not to do something that would ruin the happy day, but Sebastian had everything under control. Besides, James was introduced to the meaning of fear when Thalia promised him a fate worse than death if the criminal screwed this day up: She had promised to burn each and every one of his favorite suits and make him watch as the expensive fabric turned to ash before his eyes.
Personally, Sebastian had loved the fear that sparked in his husband's eyes at the threat, proud that his daughter could cause it because that meant she could do it to Hamish if he tried to do anything she didn't approve of. He wouldn't have to worry about her, she knew how to handle things that needed to be handled, and she did so with grace. But even knowing all of that, a part of him did worry, it worried so much that he just wanted to pick Thalia up and never stop running until she was safe away from the dangers of the world. She's his baby, his only child, and he was probably more protective of her than most fathers are of their little girls. She's twenty-three now, a woman grown, but he still saw the little girl that would come to him when she had bad dreams.
"You look tense," Jim drawls, his finger working its way around the rim of his champagne flute.
"It just doesn't seem possible that she's getting married," Seb returns, nervously tapping the table with his knuckles.
"Mm-hm, except she's not getting married, she already is married. Remember, you walked her down the aisle of that giant church and sent a death glare at our new son-in-law through the entire thing? Poor kid looked like he was about to wet himself." Sebastian remembers that fondly, he remembers the subtle shaking of Hamish's hand as he envelopes Thalia's hands with his. Sebastian also remembers the night before, when he had threatened Hamish with a slow death if anything tragic befell Thalia.
It's not until a small hand tapped his shoulder that Sebastian is brought back to the real world, finding his daughter smiling down at him with her hand outstretched. "Come dance with me, Papa," she commands softly. He can't stop his own smile despite his worry, taking her hand and leading her out to the middle of the room near where Molly and Lestrade were dancing.
For a brief moment, as Sebastian twirls his daughter around on the dance floor, Thalia is his little girl again and they're dancing in the living room of their flat with an old rock song playing softly. Nothing else exists in the room except for his baby girl, the baby girl that grew up much too fast without Sebastian's approval. It was in that moment, before James smoothly cut in, that Seb realized that he wasn't losing his baby, and if Hamish has a problem with Sebastian visiting, then the young man was in for a big disappointment.