Dave's starting to think he's going a little crazy, because there's something about Gamzee that's different from Tavros - not something as simple as build or personality, but deeper, like...like taste, or smell. Maybe he's been spending too much time around Terezi, but...yeah, Gamzee tastes and smells like indigo, whatever that means. It's sharper, more biting than Tavros' deep, rich chocolate brown, and fuck.

Dave echoes Gamzee's groan with one of his own, as the troll shifts slightly and a spark of pleasure/pain goes racing up Dave's spine. It's very possible that he blacks out for a moment, due to sheer sensation overload, his eyes rolling back behind his shades.