Optimus would never admit it, but it was Megatron's words that pushed him over the edge.

He couldn't hold his gaze; not with that overload surging through him, harder and sharper than it had any right to be after all the irritation. Frame bowing back, arching to the fullest extend of his remaining strength, Optimus clenched down, optics dimming and silently crying out as charge and sensory data overwhelmed his entire body.

Prime shuddered around his Highlord, perfectly-corresponding valve locking around that too-exact spike, heated walls fluttering contractions, uncontrolled as the surge was released.

Optimus sagged once he was spent, too drained to do anything but clench and pant waste-heat.