In any city, in any country, go to any large forest you can get yourself to. When you enter, walk until darkness falls, getting as deep into the forest as you can. When the sun vanishes on the horizon, ask to visit someone who calls himself "The Holder of the Pact". A chilling wind will rise up behind you, biting into your skin. Walk further into the forest. As dusk settles into night, you will come upon a rustic stone well and a hooded man standing near it. Walk to the well and stand on the opposite side of him. Sounds, faint and far away, will emit from the well. Do not look into the well, for even a glance will erupt horrors unto your mind and drive you to lunacy.
In a dark, crooning voice, he will ask you your name. Tell him the truth -- a dismal fate is all that awaits a liar. Your name will echo in the well. The sounds will grow excited and louder with your name. Hushed voices below whisper your name, barely audible above the growls. Hold out your hand over the well, and the hooded man will chant in a tongue that makes your knees weak, and your body shake with chills. He will slice your hand with a dagger, and your blood will drip down into the well. The sounds will grow louder, almost unbearably so. The whispers of your name will become moans of want, calling you to the well. The hooded man will respond to only one question: "Who else has made this Pact?"
The noises in the well will quiet down as he answers. He will answer you in times dating back before books, explaining the life of each person who has ever made this pact, hundreds of people. Many had different reasons for doing it, and some had the same reasons as you. No matter the reason however, they all shared the same fate. The hooded man will tell you their cruel death and their pitiful existence thereafter. All of them were thrown into damnation, their afterlife filled with torturous hells that make your skin ache and your stomach sick. He tells you of one person, the only person who successfully gathered them all together. Once his story is finished, dawn will be nearly broken. An onyx black velvet hand will emerge from the pitch black well. Telling where the well ends and the arm begins is impossible. The hand will be clutching a black heart. Take it with your uninjured hand.
The Dark Heart is Object 103 of 538. You have the Object, but the denizens of the well have your name and your blood. Do not break the pact.