You decide that you really want the dragons to trust you, but at the same time, you really don't want to have to kill one of your own kind.
You head for an exit, and just as the dragon had said, it was sealed by a wall of piled rocks. Knowing that you only have about half of your magic left after your Terrestris Maceria spell, you decide to use the smallest amount possible. Focusing again on on the magic, you say the words of power. "IMPELLO TERRA!"
The spell activates, and you focus it into pushing out the boulders at the bottom of the pile. The rocks on the top roll out of the cave's mouth, and down a steep hill, opening a gap at the top easily wide enough for you to slip out of. Feeling very proud of yourself for only using a very low level spell to accomplish your goal, you climb over the remaining pile of stones.
As the dust clears and you are able to see again, you see something that makes you feel very sick indeed. One of the larger stones that had rolled down the hill had crashed into a man in full black armor. Even from this distance, you can see that he was crushed to death underneath the boulder as they had rolled together to the bottom.
You run over to check on him, knowing he is dead, but making sure anyway. You yank of the helmet to come face to face with an older man with dark brown hair and a bushy mustache. You shed a tear and give a small prayer over his body, using your hand to close his eyes.
In a sudden spontaneous decisions, you look for his sword. You find it a little ways back, and pick it up. You return to stand above the mans body, and raise the sword above your head. Closing your eyes to halt the advancing tears, you swing the sword down clumsily, and cut his head off.
"Gods, forgive me..." you say quietly, holding your breath, and you pick up the mans head after placing the sword in your belt.
You return up to the cave and enter through the gap you created. Wandering back to the main chamber is slow going, and it gives you time to think. You convince yourself that the man died by accident, whether you had anything to do with it or not. He was killed by a rock, and not you.
You also argue to yourself that having the dragons trust you will benefit both the races, and decide that borrowing that man's head was necessary.
Without even noticing it, you have returned into the dragon's chamber. "Very good human, you are diligent in your goal of gaining our trust. You now have it" the male dragon says.