Back when Syaoran was young, his mother told him that someone needed to meet him in another world. That was Sakura, and Syaoran's father passed on his sword, and his name, to Syaoran. But he could only stay on the World of the Clow for a week, and during most of that week, Sakura could not touch anyone or eat any meat or fish, because she was undergoing a purification ritual. But she bonded with Syaoran and wanted to touch him before he left.
Syaoran may have made friends with Sakura, but her brother. Toya, doesn't trust Syaoran, and takes every chance to torment and tease him, which Sakura doesn't like at all. She tells her brother that he might be older and bigger, but he's still a child, which shakes him and makes him stop tormenting Syaoran.
She offers to show him the stars at night from the top of the castle, and Syaoran accepts. But when the time comes, Sakura says she hears a sound, like a bell, coming from the ruins of the Clow temple, or like the sound of something clashing together. She begins floating in the air, and has a vision of rushing waters beneath the temple. She calls out to Syaoran, telling him not to come, that it isn't safe.
Her father comes to see what happened, and tells Syaoran that during the purification ceremony, no one but the High Priestess, the Royal Family, and Sakura are allowed in the temple. And on the final day, even the High Priestess cannot enter. But Syaoran isn't a member of the Royal Family. He isn't even from this world. So he isn't bound by the rules. Also, the waters allowed him to be there before, and even the waters seem to love and want to protect Sakura. So it is possible for him to enter the temple when Sakura is supposed to be alone. Even if she has told him it isn't safe for him in the vision of the future that she had.
Syaoran goes with Sakura on the final day of her purification ritual, and she asks him why, and he says the Royal family okayed it because the water in the temple let him be. She says that the water likes him, too, and he asks what she means, but she gets flustered. Since it is his final day in the kingdom, she hopes they can spend time together when they can touch, after the rite is done.
But during the ritual, a portal opens in the purification hall, and Fei-Wang Reed looks through. He casts a spell on Sakura, causing black wings to mark themselves on her body. Syaoran tries to reach her and touch her, but fails, due to a hesitation. He calls out to her, and she says, "My true name is..." but never completes the sentence as the Wings touch her.
Syaoran wonders what the wings mean, and Fei-Wang tells him it is a spell of death. When the wings finally cover her body, she will die, and Fei-Wang will have his wish fulfilled. What that wish is, however, he doesn't say. Syaoran attacks Fei-Wang, but the magician is too powerful for him, and he is badly injured. Fei-Wang is surprised by Syaoran's attack, and says that the next time Syaoran attacks him, he will die, but Fei-Wang will use him to fulfill his wish.
Injured, Syaoran passes out, and when he awakes, he is in Yuko's shop. She tells him his injuries are worse because he attempted to resist coming back to earth. He asks Yuko about the spell, and she confirms that Sakura will die if the spell is allowed to proceed, but the price of saving her life is the life of another. She asks Syaoran if he is willing to pay that Price with his own life. He isn't, but he isn't willing for Sakura to die, either. He wants to save her, and he asks Yuko if she will return him to the Kingdom of the Clow so he can find some way to neutralize the spell.
She says it is possible, but it will be a one-way trip, since no one in the Kingdom of the Clow has the powers to Dimensional travel, yet. And he will have to leave behind everything and everyone he ever loved on his home earth. He agrees, and returns to Clow after his wounds heal. But despite his many travels to distant lands, he could never find any way to erase the mark. And when her 14th birthday came, at the time of her second purification ceremony, it struck, and the High Priestess Queen gave her life to keep Sakura alive by literally stopping time. Syaoran thought that there was only one way to save her, to go back in time and touch her before the spell could. But how could he do it?
Well, this was completely unexpected. It was great to see how Syaoran came to Clow and why he came back and chose to stay, but can he really go back in time and change it? And what will the effect of those changes be? In the beginning of the series, we don't see that Sakura's mother and father are being alive at all, so perhaps going back in time somehow was responsible for their deaths, instead of them surviving until she was 14, as we see in this timeline. And what was the cost of being able to go back in time to prevent the spell from touching Sakura and eventually kill her?
At this point, we don't know, but it would definitely be a big price. After all, the price Syaoran paid for returning to the Kingdom of the Clow was very heavy also, and since he seems to have retained his memories of two lifetimes, he is actually far older than he looks, which seems kind of unnatural.
At this point, I am more than interested in seeing and reading more, and finding out what went on, and the cost Syaoran paid to return back in time. For that matter, there are hints that Watanuki Kimihiro, from XXXholic, is some sort of substitute for Syaoran, or is another version of Syaoran himself. We know, from XXXholic that Watanuki can't even remember anything of his past, or his parents, or their names, and that he has completely paid some kind of price for Syaoran. But what is their true connection? So far, we don't know. But I want to find out, and I'll keep reading until the end of both stories.