Sookie placed her mouth over the wound, drinking is blood willingly, because she wanted to strengthen their bond and try to override the one he'd just formed with Helix some. It was perhaps the first time she'd done so, save the time he tricked her into sucking a bullet from his chest, which didn't much count for anything save it being one of the times he was selfish and underhanded—of which there were plenty.
When she'd had enough, she pulled her mouth away, lips stained red.