Quatre smiles, startled, into the kiss (inside he is feeling triumphant, and surprised, and touched). It's mild, a hello-I-like-you reminder, but Quatre shifts slightly so it's easier to keep kissing, setting down his tea on the counter as his free right hand goes to Trowa's left arm.

Maybe kissing forever is an unlikely goal, but kissing for right now is something he is all in favor of.