He always felt a small bit of disbelief that Leonard would go through with these things, right up until Leonard was actually doing it, fulfilling what he asked of him and so well. It was nothing about Leonard's ability, but rather accepting that someone was willing to fulfill this. So his eyes were slightly wide, mesmerized by Leonard's lips against his finger.

Spock could recline. He took advantage of one of the beds to sit back on it, knees on the outside of Leonard's hips. You may massage the palm. Warmth, a quiet burn. Or you may apply suction to any part of the fingers. A sharp thrill; he straightened his shoulders back a little. Teeth are also allowed...within reason. The excitement of courting danger bubbled up there. Anything too much would take the pleasure out of it (and he wasn't that kind of Vulcan).