That humming, as it set the sensitive metal vibrating inwards, made it very hard to stay still. It joined with the slight tremble of his own frame from the effort of staying still and pinched sensory nodes between them in a feathery sort of pinch.

"Ah--- no. Not... intentionally." Megatron spoke through the gentle flicker of fiery charge from Orion's tongue dipping in and out around the rim with the determination of someone who wouldn't give in to the wavery static that his vocaliser wanted to break on.

So instead he tilted his helm back, forced his vents back into the default slow cycle, and kept the desire to move from the charge building up, from Orion's blasted lips and tongue, to a spiraling flex of his valve.