Spoilers ahead... Read at own risk.
I've been thinking about this and it did occur to me somewhere during the final straight that the Marquis of Sui's pearl or sui hou zhi zhu... was more than just the holy grail of an unholy gem hunt. Anybody and everybody... with the rare exception.. was moving heaven and earth looking for it. Not to mention the egregious stealing, killing and destroying in the process. Legend states that it was an object left behind by the previous dynasty's ruler, a key or map to a treasure of untold wealth. On the surface the drama seemed like a ridiculously convoluted treasure hunt. With each rewatch, however, I'm inclined to see the pearl as a recurring motif intertwined with the leads ongoing dynamic and resolution. For everyone else the pearl is about power and the promise of riches. However, for Xiao Song and Ran Yan, the pearl takes on a different dimension. For them it represents love and trust.
To my great delight and relief, the elusive pearl turns out to be real. Not a just a nebulous plot device as I had feared. The veritable carrot stick for the committed. Forged from a meteorite it possesses curative properties. One can't take these things for granted sadly. C dramas especially have a way of hyping the importance of rare, valuable objects, only for the endgame to completely let you down when on opening the chest, it's empty and apparently we're all suckers for wasting 40 something television hours waiting for the payoff. Thankfully it's not the case here. It gets found... much earlier than expected. Because finding it although important is not as important as having it in the right hands. Which means someone who doesn't want to start a war. Someone who cares about peace in the land. Someone who cares about the masses.
The fascinating part about the entire project is that if you've watched the drama up to Episode 26, we are told that our hero, Xiao Song has had the pearl in his possession since he was a boy hidden inside the tooth-shaped pendant that he carries around for luck. On hindsight it is a family heirloom credited for helping him survive past childhood. So this gem which every man, woman and dog has been looking for, for at least 12 years, has been in the custody of Chang'an's preeminent investigator unbeknownst to everyone, our hero included. The irony of course is that he was tasked in a top secret mission to track down the pearl by the emperor and is sent to another province to chase up on a clue that could lead to its location. This now becomes his dilemma because his grandparents were Sui loyalists and custodians of the pearl until such time when the Sui dynasty is revived. This has serious ramifications for the Xiao family in this current regime. Treason goes right to the top of the list. With all that to consider, Xiao Song is unable to surrender the pearl immediately and say, "Look Your Majesty at what I found when I stumbled into a secret chamber in the Xiao mansion that my grandfather built."
Now, when he first arrives in Suzhou, the whereabouts of the pearl is the nagging mystery but what he does find first are dead bodies and a gifted female coroner, Ran Yan, who later becomes his wife after the two become entangled in a series of misadventures and cases which involve the pearl one way or another. Judging from the way their trajectories intersect either by circumstance or by choice, their eventual meeting seems inevitable. He is an investigator of crimes, she examines dead bodies... it's a match that could only be made in heaven... as they say.
During the fourth arc he marries her in unseemly haste in part because he really does like her, plus the opposition is noticeably absent and in part to get her out of her family home where she has become the target of an in-house killer. (He has the knack of killing multiple birds with one stone) After a near-death experience the two afterwards discover that she is a beneficiary to a definitive clue that provides key information about the pearl. Before then she's largely in the dark about matters pertaining to the pearl. It becomes clear at that point that their fates are intertwined by the gem. On this occasion, he helps her reveal secrets behind her mother's death and brings the culprit(s) to justice.
The villains of the piece are the Huo Qi Sect (Lit: Fire Flag Sect) and their agent is the enigmatic Su Fu who is incidentally Ran Yan betrothed. So at first he gets up close and personal because she's a conduit to the tight-lipped Xiao Song. He is one of the first to pick up the fact that Xiao Song has feelings for Ran Yan and is not backwards about using that to get a reaction, thinking it would cause the latter to make forced errors. The organization's primary goal is to grab the pearl for themselves, use that to find treasure in order to fund an army to overthrow the current regime.
Sometime later on returning to Chang'an, Xiao Song gives his pendant to Ran Yan when she becomes the subject of a contrived sex scandal. It is his way of staking his reputation on her reputation and publicly declaring that she is his wife. He asks no questions of how she gets into the predicament but hands over the heirloom as proof (and pledge) of his unequivocal trust in her. However, behind the scenes he finds the individual(s) involved and finds the time to shame them publicly thus restoring the lady's good name. Neither at this stage are aware that she's now the unofficial custodian of the elusive pearl. But it is another big moment for them because he proves... yet again... the lengths to which he will go to protect her.
As his newly re-contracted wife, Ran Yan becomes the key to his locating the pearl within the family manor when spies in the Xiao household lead her to uncover a family secret. She is also instrumental in shedding light on the mysterious deaths of Xiao Song's first two wives which we discover later are also related to the pearl expedition. They both agree amicably that he should take back the family fossil for safekeeping while working out how to hand the object to the emperor without implicating his family.
The couple's biggest trial comes when Ran Yan is manipulated into helping Su Fu retrieve the pearl from Xiao Song. It turns out to be an elaborate plot to entrap her and wreck his credibility. Xiao Song is led to believe that she betrayed him because of Su Fu, not realising that she had kept faith with him and the pearl was right at his doorstep.
Despite feeling like a betrayed sap, Xiao Song is still deeply in love with her. Even while keeping up the pretence of being indifferent, and having moved on, he is busy behind the scenes helping her with her latest predicaments. All this time he still thinks that she is still in love with Su Fu, driven to desperation for his sake.
On her side, she thinks she has lost his love entirely when she was all set to start afresh with him after dealing with Su Fu's dilemma. She labours under the impression that his love for hasn't withstood the test of her misadventure with the Huo Qi sect and the ensuing political fallout. Hence the divorce. She doesn't know that it is the result of a royal decree. He on the hand uses the divorce as justification to keep his distance, possibly to protect her and himself from their enemies who are sufficiently unscrupulous to use their relationship to get at him. The pearl going missing doesn't enter into her thinking.
In a wonderful monologue that she gives while being held hostage by a deluded serial killer, in the presence of the man she pines for, she bitterly recounts her own experience of disappointment with love. In her mind a certain man promised her the world and built up her expectations of what love was like. He would love her for the rest of her life. But as soon as the crunch came, all the wonderful build-up went up in a puff of smoke. When she finally realised what love was and tasted the sweetness of its fruit, the transience of it left a bitter aftertaste. There is only longing from a distance because all efforts to close the gap lead nowhere but pain. Her despair and bitterness blinds her to what is plainly obvious to the rest of us. Despite everything he still loves her and his primary impulse is always to protect her even if it hurts him in every way.
When he's home nursing an injury, Xiao Song ponders over her cryptic comments wondering if he's misjudged the situation with her. Dad walks in and challenges him to act openly in concert with his heart. He sadly tells his father that "her heart is not with me". The older man returns the heirloom pendant and says that Ran Yan left it behind. Unfortunately Xiao Song still believes that she's given the pearl to Su Fu (and by extension, his enemies) so he doesn't bother opening the family heirloom to check.
Therefore, Xiao Song's search for clues regarding the pearl clearly parallels his journey to find true love. At the start of the drama we see that he has memorized the map of Suzhou city to give context to his mission. What awaits him is far more important to him personally, it is his own journey's map to grappling with a love that demands everything from him including his unquestioning obedience to the sovereign.
Therefore the fate of the pearl becomes analogous to his relationship to Ran Yan. As long as it remains hidden from his view, he thinks that love eludes him. When he finally rediscovers the pearl in his possession, he realises that he wasn't betrayed. He had her heart, her love all this time so the sacrifice to marry Ran Mei Yu feels much less onerous than before. Subsequently what he needs to do is trust her with his honour and his life.
As for Ran Yan, her moments of petty jealousy proved that she was gradually responding to his overt gestures. For the first time in her life she can see love in all its manifestations writ large with no strings attached but is hesitant of what the ramifications are for her. She is genuinely angry when he sends her back to her cousin's place for safety. All that happens as she continues wearing the family heirloom publicly in plain sight.
She inadvertently interrupts a sting at the brothel and makes her first public confession. He's hers and nobody gets to lay a finger on him. And yes, he's unbelievably chuffed. And hopeful that better things are in store. ;)
Not long afterwards she leads him to a secret place in the Xiao manor where they discover the pearl's location together. This changes their dynamic. They share a secret about the Xiao family. It gives him hope that she would really become family finally.
She believed that she had his love for a time but thought she had lost it for good. A single mistake of being too smart for her own good cost her the love that had promised her the world, a love of a lifetime that would never let her go. So she thought. In reality she hadn't lost his love at all but his trust. Very Scarlet Pimpernelish.
Although the Lady Dongyang had her own agenda in doing so, RY's eyes were opened to the reality that the love that she thought was lost to her forever was there all the time working in the background -- saving her, protecting her and helping her. Now with a new set of lenses she can see beyond the facade that he presents to her. So she goes to rescue him from a fate worse than death -- marriage to Ran Mei Yu.
In Episode 35 when he hands the pearl back to her for safe keeping if anything should happen to him, she is surprised that something so valuable should be placed in her hands but he tells her that he trusts her. Even when all the conspirators are out to get them there is a sense that now they are of one mind and heart, they are an unstoppable force of nature.
Spoilers ahead... Read at own risk.