Well... Nice job Starr... Really...
But I have a surprise for you... Remember that stone? Well It's not just for show. 
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Mat begun to cry when Sarrani left the restaurant... He loved her, and she left him. He had to follow her. But then a man in black common clothes sat with him.
"Who are you?" Mat asks offended.
"I am someone you know." The mysterious man smiled.
"I don't know you..." "Listen to me Mat!" The Stranger interrupted him. "You do know me! This is not real... This is an Illusion."
"What? You're cra..." "Stop it!" The stranger hit the table with his hand. "This is not real now. This was real before. This is a vision. You're in a Tomb now. Remember, you entered it together with me!"
Mat was surprised, he began to sweat as if he was fighting with something very, hard... "George? I... I... can't believe..."
"You can't believe me!? Then how come no one but you can notice me."
Mat then noticed that people around have been staring at him... It looked like he was talking to himself. The waiter was there asking him if everything was okay. He didn't seem to notice him. Mat smiled and just said... "This is not real." George smiled back and everything started to fade...
...
"You knew my family." The stranger said to Leina. "What? Who are you?" The man continued sadly, as if she didn't say anything. "You knew my family, you knew me, and yet you didn't tell me." Leina was wordless. She didn't know what was this man talking about. "You must be mistaken. I don't know you."
The man huffed, as if he was annoyed. "You don't know me, yet you said goodbye to me minutes ago. Look at me face carefully." She raised her eyes to look at him, and she did notice a resemblance to someone... "You do look like James, and like George a little. but I..."
"Listen to me Leina this is not real. This is a vision of your past." "What? Get away from me." Leina sounded confused... "I'm George and you entered with me into the Elder Tomb." George looked at her and stepped towards her. She backed away a little. "You know this is true. Search your feelings, this is not real!" He pointed with his hand showing everything around him... "This is not real" Leina mumbled... "We were in the Tomb, and I died." Leina eyes started to fill with tears. "I remember" she whispered "This is not real..." She moved towards George to hug him, but then everything started fade...
...
A strange man in black common clothes was walking through the bloody sands of the arena. Riordan noticed him and grabbed his weapon by the barrel demanding the man's name. The man stopped, he was unarmed. He looked at Kain's body, and then back at Riordan.
"This is not real, Riodan!" the man spoke out loudly "Your brother lives! He awaits at the Tomb Entrance, remeber?"...
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Haha surprised!?
I know you like plot twists, but if this screwed your plans I can make something different.
But I said that stone has it's powers, especially in the land of dreams, it records memories. Remember how I said that it records what happens around him? And since that beast trapped them with their own memories the stone activated itself to help them be free of it. And because the George was sucked into it he was shown as the one who will save them.
And this way. George knows what happened. So he'll know what happened to Rioardan.
P.S. You can write that part when George is convincing Riordan that he didn't really killed his brother and that it's not real. You can take control of my character for that part 