One of them is King Abdullah of Saudi Arabia. The other is President Bush.
So what happens when the president comes calling on the king? Call it the battle over bedtime.
It appears Bush is willing to make some concessions for the king. Bush, scheduled to arrive today in Saudi Arabia on his first visit to the kingdom, has an appointment at the palace beginning at 9:05 p.m. local time -- the time he usually is getting ready for bed.
The big question is how long will the president stay. "You know, this is a matter of great sensitivity," a senior Bush administration official said with a smile.
Bush stayed up late -- for him -- on Sunday for a dinner at a remote encampment where Abu Dhabi's crown prince, Sheik Mohammed bin Zayed Al Nahyan, raises horses and prized falcons. The president did not get back to his hotel until after 9:30 p.m.
Late meetings are an Arab custom, partly because it is so hot during the day much of the year.
Saudi Arabia promises to be the latest night on Bush's eight-day Mideast trip, with stops in Israel, the West Bank, Kuwait, Bahrain, the United Arab Emirates and Egypt.