Theo didn't wake up immediately, either not heating Greg at all or hearing the timbre of the voice and deeming it soothing enough not to need to wake up. The touch though - Theo couldn't associate touches with being soothed a lot of the time - the touch woke him up, without gasp or flailing or yelp, just in cold, subzero silence as his arm went to flick his wand out...
... his wand wasn't there. THAT had him confused and flinch away from Greg a little until he managed to wake up.
"Greg?" he queried, leaning back against the wall, his voice heavy with sleep, his eyes clouded in confusion and slumber and his demeanour not quite awake. "What're you doing here?" as was evidenced.