The first thing he ever feels is anger.
It pulses through him in cold/hot flashes that taste of bared teeth and slashing claws, shot through with tense frustration and jagged anxiety. Slowly, the mess of feelings resolves into two separate sources: one worried and frustrated and anxious and protective, the other distant and resentful, tense with restrained violence. Their feelings splash and crash and swirl around one another, and, even more slowly, he begins to realize that none of those feelings are his.
He doesn't have much time to process this revelation before his whole world shifts and tilts, and a new, beautiful sensation distracts him from the sense of others' minds. The moonlight is faint, shining through his eggshell; instinctively, he begins to scratch at the inside of the shell, answering its call.
A sharp, loud sound overwhelms his senses, and he cringes back, too frightened to reach for the moonlight. Muted noises from outside the shell; a further swirl of feelings in the two minds he can sense, protective-angry-love clashing with impatient-resentful-anger. A rush of motion, and then a warm, calm stillness. Sheltered by the protective feelings, he tentatively scratches at his eggshell again. It rolls and tilts, then settles. Faintly, he begins to sense another presence, small and new like him, not big and strange and complicated like the two angry minds.