They are from the same village, the same tribe and the same clan.
Once as close as brothers, they rose together in Yemen's military, the same lofty desires. One is an Islamist with reputed links to Osama bin Laden. The other is one of US' closest allies.
For 32 years, Ali Abdullah Saleh and Major General Ali Mohsen al-Ahmar have controlled Yemen, the former as its ubiquitous president and the latter as its invisible yet most influential military leader. Now, they are engaged in a highly personal battle to shape the future of Yemen and their own places in history.
"They are like Siamese twins, one body with two heads," said Hassan Zaid, a top opposition leader.
"Now, each head is trying to cut off the other's head..."
When snipers loyal to Saleh killed 52 protesters on March 18, Mohsen declared his allegiance to the uprising, triggering a wave of high-level defections from the military, influential tribes and the government. Mohsen, who controls much of the military, was once widely viewed as Yemen's next leader until Saleh sought to anoint his son Ahmed as his successor. Now, Mohsen has become instrumental in pushing for Saleh's departure.
And the questions now, on many minds here, is whether the tensions between Yemen's two most powerful leaders will lead to a peaceful transition of power or to civil war.
Many protesters said they appreciated Mohsen's support, but also viewed him as a part of the current regime, of why they needed a new Yemen. "We need a civilian government running the country," said Mosab Qirshee, a student. "We don't want Ali Mohsen to lead us next."
(In association with The Washington Post. For additional content from The Washington Post, visit www.washingtonpost.com )