Okay, this riddle was written by my aforementioned friend. She wrote me last night and said I could share it with ya'll. It's actually in the form of a short story called "Gideon's Headstone". 
Quote:
Sedanien lingered by the headstone while the others who had gathered for the funeral disassembled. She couldn't believe he was actually gone. She thought that she would feel relieved, after all, Gideon had been the most infuriating, insufferable, egotistical nut job that she had ever had the misfortune to travel with. And really, she hadn't been traveling with him, he had followed her around like a lost puppy. She used to dream of the day when he would leave her alone.
But now that that day was here, all she felt was a deep sorrow. Though she didn't really like him, she wouldn't say that she disliked him. She certainly didn't want him dead. Despite his shortcomings, Gideon had also been the most interesting and unique man that she had ever met. The world had lost one of its treasures, and that was nothing to feel smug about.
At least she had been able to give him the headstone that he had wanted. It suited him, as it was completely unique and made just about as much sense as the man who had described it to her did. At the top of the headstone, above the only name that he had ever given her, 'Gideon', were the words “Life, Death... Death, Life”. Sedanien had never understood why he wanted this, and when she had asked him about it, interrupting him while he told her about his ideal death and ideal funeral, he just grinned his peculiar, lopsided grin at her and his eyes twinkled mischievously. She supposed that it meant something like 'From life comes death and from death, life'. That was the sort of backwards, round-about way of talking that he was always so fond of. Under his name, in place of a date of birth and a date of death, was another riddle, “It is not what it is. I am what it is not. Therefore, I am what it is.” Sedanien couldn't fathom what he could possibly mean by this. Of course, knowing Gideon, that was probably the point.
Sighing, Sedanien turned away. Simply wishing that things could be different wasn't actually going to change anything. She was, bu now, well acquainted with death, this was just another one that she would have to get used to. When she reached the edge of the cemetery, she looked back and was astonished to see a man standing in front of Gideon's grave. She had no idea where he had come from, it was as if he'd just appeared out of thin air. She ducked behind one of the taller monuments, hoping that he hadn't seen her. Gideon had never told her about having any friends, those few who had come to the funeral were mostly just people from town who had heard of the deceased mage. So, to see someone who seemed to have actually known him greatly intrigued her.
The man was certainly dressed for a funeral, though Sedanien thought that the black, feathered mantle he wore over his voluminous black cloak was a little much. He absently tucked a strand of long, dark hair, which had blown into his face, behind an elven ear. The ear caused her to pause. Gideon had such ears. The point was not as pronounced as it was in regular elves, but he seemed too pale to be a hybrid. Maybe he was something altogether different, as Gideon had been.
Sedanien looked close at the man's face, which seemed to be battling two conflicting emotions. Apparently, he couldn't decided whether he should be annoyed or amused. Perhaps he was no friend of Gideon's after all. If he was, why would he be amused by his death?
Then he spoke, his low voice barely louder than a whisper. “Are you proud of yourself now, brother?”
Sedanien frowned in confusion. Brother?
The man adopted a sour expression. “You managed to have me come to your funeral. I really don't see why I'm here. Why is this so important to you? Both you and I know that it's completely pointless.” He smirked. “You even managed to tell everyone as much and answered your own riddle.” The stranger chuckled mirthlessly. “But they will never understand it, will they? No one will ever see. Except for me.” The man shook his head. “Listen to me. After all these years, I still occasionally sound like you.” His small grin faded. “But that is why, isn't it? You wanted me here because I am the only one who knows you well enough to understand that which you put so plainly for all to see. You had it all planned out, didn't you?” He scowled. “I don't like being manipulated, Gideon. I have no love for your silly games.” Sighing, he looked at his hands. “But a promise is a promise. You know I always keep my word.”
Sedanien watched, transfixed, as the man's hands erupted in violet fire. The flame writhed and twirled, forming a shape. Eventually the fire died down and darkened until it became something solid.
“Here is your flower, Gideon.” The stranger knelt down an placed the newly formed flower against Gideon's headstone. Standing back up, he gazed at the grave a moment longer before looking directly at Sedanien, or rather, her hiding spot. She thought she saw him smile before she ducked back behind the stone, out of sight. When she risked glancing back out, she saw him walking away in the opposite direction. After he was gone, she walked back over to Gideon's grave.
Sedanien knelt down and touched to flower that the dark stranger had created. To her surprise, it felt exactly like a flower should. The stem and leaves were black with the occasional thorn, while the petals were shades of purple. They started out a dark plum color that was almost black and got progressively lighter as they got closer to the center of the flower. The venter itself wa the same deep violet of the eyes that had found her hiding place.
Looking back at the headstone, Sedanien thought of the stranger's words. He had said that his being there was pointless and that Gideon had said so in his riddle. He also said that Gideon had even put the answer to the riddle in plain sight.
Sedanien frowned as she read the words over and over. Gideon had been with her for awhile, so she thought that she ought to know him well enough to see and understand his message as that mysterious man had. Then something the man said occurred to her. They will never understand it. He had stressed the word 'it'. That must mean something. She read the words again, even counted the number of 'it's. And then her eyes widened. She saw it. She understood. And she was going to kill him.