Link and Zelda stood confidently beside each other. Their faces were plastered with determination as they awaited the source of the lumbering footsteps they heard echoing through the palace. The heavy wooden doors to the room were suddenly flung open with such force that the wood splintered. A hulking monster stepped through the opening. He had grey skin and part of his body was covered in dark scales. His eyes were glowing orange, and his hair appeared to be made of fire. Link instantly knew that this could only be Demise, the one whose power gave rise to Ganondorf.
Demise acknowledged the presence of the two humans with no more than a disinterested grunt as he strode past them and walked right up to the incomplete Triforce. He lifted up a large stony fist. His Triforce of Power flew from his fist and grew in size until it was the same size as the other pieces. It was inserted into the cutout in the wall, alongside the other two pieces. The Triforce was now complete once more. Demise finally decided that the two humans were worth noticing. He turned to them, his stony face still expressionless.
"So I presume you are the ones responsible for killing my servant, Ghirahim" he said in a gravelly voice. "No matter. If he can be slain by a mere human, he deserved to die. He served his purpose." Demise turned his attention to the Master Sword in Link's hand. "Ah, now I know how Ghirahim was defeated. I recognize that sword. I fought a human who wielded that sword many centuries ago. I was careless and fought him before I had reached my full power, and he bested me. I was trapped within that sword for a very long time. I will not make the same mistake again. Once I have the power of the Triforce at my command, you both will serve me or you will die. I have the power, wisdom, and courage needed to take possession of this power, so it is time for me to claim what is rightfully mine."
Demise placed his hand on the full Triforce. The room was shaken by the sound of thunder. Demise let out a jubilant roar. "Ultimate power is mine at last!" he bellowed. Suddenly, the Triforce turned black for a few brief moments. It then returned back to his golden color. Demise gasped in surprise. "What is happening?" he asked aloud. "I am not able to move. What kind of trick is this?" Demise still had his hand stuck to the Triforce.
Zelda walked up to the Triforce and placed her hand on it. Link soon joined her and placed his hand on it last. "You may have the balance of attributes required" said Link. "But you do not have them in measures sufficient enough to overcome the trap I have laid for you. This will be your end, Demise. You have courage, but not enough to face me without seeking shelter under the power of the Triforce first. You have wisdom, but not enough to avoid walking right into this trap. You have power, but not enough to save yourself from the destruction we are about to unleash upon you."
Link drew the Master Sword and held the blade up to his forehead. "I'm counting on you" he whispered to the sword. He looked right into Demise's fiery eyes. "I should tell you about the Triforce you are trying to claim dominion over. Because it is derived from a careful balance of the essences of three goddesses, the Triforce may appear outwardly to be very simple, but it actually contains some very complex magic. Its existence is tied to reality itself. And because of this, it contains several magical safeguards to prevent misuse. The safeguard you knew about was that it requires a balance of the three vital attributes. Well, I activated a safeguard that you didn't know about. My Master Sword is now imprinted with the necessary attributes, giving it the ability to act as a key of sorts. The safeguard you knew about was just the outer layer. I used my key to unlock the inner layers, and then I altered the magic contained within. I activated a trap I designed just for you, and now I will turn the power you sought to claim against you and use it to utterly annihilate you. May you perish and never again be reborn!"
Link moved the tip of the sword close to the triangle he was touching. The triangle turned black as the Master Sword drew near, signaling to Link that this was the wrong one. He then moved it over to Demise's triangle and it also turned black. He finally moved it near Zelda's triangle and it turned white. Satisfied that he had the right triangle, Link shoved the blade of the Master Sword into the triangle. The light died out of that triangle and was sucked into the Master Sword.
"One down, two to go" said Link as he moved the Master Sword to Demise's triangle once more. It turned black again, but Link's turned white this time when he brought the Master Sword close to it. He shoved the blade through his triangle, and it too had the light sucked into the Master Sword. Finally there was just one left. Demise's triangle was white now, so Link used his sword to take that light too. The blade of the Master Sword was now glowing brilliantly white. The light radiating off of it was almost blinding in its intensity.
The three triangles of the Triforce were now a dull golden-brown color and lacking their usual glow. A black upside down triangle suddenly appeared in the space in the center of the three other triangles. "Step away from the Triforce, Zelda" he said softly. She did as he asked. He too removed his own hand from the Triforce and stepped back.
"What are you doing?" demanded Demise. "You don't know what you're doing! Stop it!"
Link let out a mighty yell as he drove his glowing blade into the black triangle. The light from the Master Sword overwhelmed the black triangle and turned it a golden color. The other three triangles then had their golden color returned. With the addition of this fourth piece of the Triforce, it was now one large triangle.
"I suppose we should call it the 'Tetraforce' now" remarked Zelda. Link nodded. "Makes sense to me, seeing as how I just added the fourth piece it has been missing all this time. Now we just have to let the completed Tetraforce finish this for us."
The Tetraforce suddenly erupted with a harsh burst of light. It enveloped Demise. His rocky skin began glowing red, like embers of a campfire. Soon his whole body was turned into flame as he was sucked into the Tetraforce. One final flash of light was emitted from the Tetraforce, as if in confirmation that Demise had been completely annihilated.
Link grabbed Zelda's hand. "It's over" he said. "After all of this, it's finally over. Let's go home."