As the kunai reaches short range above you, you still haven't removed it in a way he thought you would... instead you let it run, even come close to you as you were too preoccupied with finishing your hand seals. ''I'd simply side step out of the trajectory of the kunai as i finish my jutsu'', and that was when it happened. As you finished your Water jutsu, due to the way it's made, it's not instant. First, the clouds must gather, then, the rain drops have to fall on Roy, pointing his location out to you, so that you can then tell the dragon of his location.
But this never happens. Just as you finish your hand seals, Roy's invisible hands had formed a seal which causes Fire to suddenly burst out from the Kunai which is now only inches away from your body, more specifically, your face. The sudden burst of Fire presents no warning. This sudden burst would not only catch you off guard, but due to it's close proximity, it'd burn your face, melting your skin off to a point of no return.
This is a secret jutsu taught to me and one other... the last man to face it was the Yellow Flash of Konoha, and even his reflexes could not save him.
As you're blinded, and screaming in pain, Roy would throw a further two Kunais, one with a paper bomb attached, and another normal. Both are aimed to hit you in your chest area, and the one with the bomb timed to explode upon reaching short range. The one without a paper bomb is slightly in front so that if the explosion is allowed to occur, it'd only push it forward due to the force of the explosion.
Just then, rain began to fall from the clouds, something Roy sensed as opposed to felt. A symbolic feeling for Roy as he heard the screams of his opponent whilst the calming rain drops left their home in the clouds, but he couldn't just let it fall on him. As it reached a height 10 meters above him, energy would suddenly emerge long range all around/above him, almost out of nowhere, stopping only in a specific area around you (diameter of 5 meters, so short range), which allows the rain to rain down on you, as if nothing was different.
The rest of the rain would strike down on the newly created ceiling of energy, just as if it were hitting the ground itself. This allows Roy to still remain un-sensed. All the rain drops which may fill up the ceiling simply go off the edges, or through the hole made on top of you. The energy isn't weakened, or damaged by the rain drops as they don't have that kind of capabilities and thus remains on field.
Assuming nothing is interrupted, Roy would cause spikes to emerge from below you, piercing your very skin.
Talking doesn't affect time frame, obviously.