He doesn't buy gifts like this for just anyone, that is for sure. Most girls he takes out he might lavish with buying their drinks all night or putting the pair up in style for the night, but that is about it. Whatever is driving Marcus to spoil Susan is only being encouraged by the way she responds to the gift. Her eyes light up and her smile has his knees feeling weak.
Then comes the light graze of her lips to his cheek and he resists, best he can, the urge to pull her to him and do something far less innocent. It's in his nature to want that, to want pretty girls like her, but he knows it isn't right. Not this one, he refuses.
Instead he places a light hand to her hip and lifts another to gently pluck from her hands the box. Without a word he is removing the necklace and walking around her, hand trailing over her abdomen as he moves. Then he speaks, soft and low with his head tilted down a bit.
"Happy Birthday, Susan," he fastens it about her neck, hand lingering on her right shoulder a moment before he steps back and turns her about to see how it looks. But his eyes don't linger on the necklace, they flicker up to catch her gaze.