If any relationship today speaks to the new dynamics in the Middle East, it is that between Syria and Saudi Arabia.
The volatile nature of those dynamics has complicated ties between Riyadh and Damascus, when the Saudi regime would have preferred more clarity. At the heart of Saudi worries is Iraq, while at the centre of Syria's preoccupations is Lebanon.
Earlier this month the two countries sought to reach an understanding that might advance their interests in both places. At a summit in Damascus, followed by a visit to Beirut, King Abdullah of Saudi Arabia and President Bashar Assad of Syria agreed to a deal that went something like this: Syria would collaborate with the Saudis in derailing the appointment of Nouri al Maliki as prime minister of Iraq, while the Saudis would push Saad Hariri, Lebanon's prime minister who is politically beholden to Riyadh, to end his government's co-operation with the Special Tribunal for Lebanon established to try suspects in the assassination of Rafiq Hariri. Syria remains the major suspect in the crime.
In Lebanon, the two Arab leaders endorsed a statement that Lebanese disputes would be settled in the framework of the national unity government. This was regarded as an effort to avert violence in light of Hizbollah's threats that all options were open to the party to undermine Lebanese support for the tribunal, which its secretary general, Hassan Nasrallah, had described as an "Israeli project".
The understanding stabilised Lebanon, but not for long. Each side felt the other had not respected its engagements. Syria, with few means to shape Iraqi affairs and facing Iranian and American backing for Mr al Maliki's return, rallied to that option. In turn the Syrians accused the Saudis of failing to push Mr Hariri to abandon the tribunal, even though they had compelled the prime minister to make a statement to a Saudi newspaper casting doubt on the institution's work and virtually declaring Syria innocent of his father's killing.
Despite the strains, the Syrians and Saudis will probably try to preserve their understanding. The Saudis are deeply uneasy that Mr al Maliki may come back, and even more so that this was facilitated by Iran and blessed by the United States.
For Riyadh, the new situation only consolidates an Iranian-led Shiite order in Baghdad, even if one can dispute that Mr al Maliki is Tehran's stooge. Consequently, the Saudis hope to gain by maintaining open channels to Syria, since both need to retain a hand in Iraqi affairs as part of their regional leverage.
In Lebanon, the situation is thornier. The Saudis have effectively signed off on a Syrian political revival there, hoping this will contain Hizbollah. However, Riyadh holds a weak hand. The Syrians have spent more time undercutting Mr Hariri than they have treating him as an ally. Thanks to the tension over the special tribunal, Mr Assad has been playing Mr Hariri off against Hizbollah to Syria's advantage, while strengthening his ties with Iran. Indeed, last week the Syrian president made a much-publicised visit to Tehran, reiterating the closeness of the Syrian-Iranian relationship.
The Saudis are gambling that Syrian self-interest will prevail in Lebanon. Mr Assad wants to dominate alone, they believe, and seeks once again to make Lebanon more a Syrian than an Iranian card. That may be true, and it is why Mr Hariri continues to defend his reconciliation with Syria, even though last weekend the Syrian judiciary issued arrest warrants for Lebanese officials and journalists, most of whom are close to the prime minister. The problem with the Saudi calculation is that if Mr Assad does reassert Syrian hegemony in Beirut, Mr Hariri and the Saudis will be marginalised.
In the 1970s and 1980s, the Saudis were at the heart of the Arab balancing game, their principal objective to ward instability away from the kingdom's borders while ensuring that no one rival gained the upper hand in the region. Syria took advantage of this, earning Saudi approval for its military takeover of Lebanon, while also aligning itself with Iran during the Iran-Iraq war, against the Arab consensus. For Hafez Assad this served several purposes: it allowed him to counterbalance his great foe, Saddam Hussein; it made gaining Syrian approval more expensive for the Arab states; and it allowed Assad to manoeuvre between the Arabs and Iran, permitting him to exploit their enmities.
Today, Bashar Assad is replicating his father's policies, but he has more to play with. Syria's rapport with a powerful Iran has bought it valuable space with respect to the Arab states, so that in the past five years Mr Assad reimposed his writ in Lebanon over Saudi and Egyptian opposition thanks to his alliance with Hizbollah. Syria has also gained a stake in Hamas, along with Iran, and therefore can hinder Palestinian-Israeli peace negotiations. And Mr Assad has opened up to Turkey, which has served as a mediator between Syria and Israel, allowing him to circumvent Arab or Iranian opposition to talks if required.
The irony is that Syria, on its own, suffers from glaring political vulnerabilities. Its influence in Iraq is largely restricted to subverting the country's security; on the Palestinian track, it is Iran, not Damascus, that is footing Hamas's bills; on the ground in Lebanon, Syria has had to depend heavily on Hizbollah during recent years, while its own partisans are feeble; and when it comes to Israel, Syria has consistently avoided a military confrontation, and remained silent when the Israelis destroyed an alleged Syrian nuclear reactor in 2007.
Yet Mr Assad has persuaded one and all, including the Saudis, that Syria is a major player. Being a good illusionist can do wonders, but it also explains why Syria is so often difficult to trust.
Michael Young is opinion editor of the Daily Star newspaper in Beirut and author of the recent The Ghosts of Martyrs Square: An Eyewitness Account of Lebanon's Life Struggle