Bashar al Assad did not step down either, and began making allies. Iran began supporting Assad by sending cargo and troops for the war. But the rebels weren't without help, Turkey was sending resources from the Persian Gulf to aid the Free Syrian Army.
In August of 2013, Bashar al Assad used chemical weapons on civilians. Later, in September, President Barack Obama, furious with the actions of Assad, threatens to call an airstrike on Syria. The US eventually backs down, but they are officially in the Syrian Civil War.
In early 2015, Turkey does something similar, they bomb the Kurdish, even while the Kurdish are fighting ISIS. Turkey, however, does not bomb ISIS.
Seeming to follow the trend, that same year Russia bombs non-government targets as well.
As of now, the Middle East is split, Rebels against Assad.
Since the start of the war, over 4.5 billion people have fled Syria. They have fled to Turkey, Lebanon, Europe, and Jordan; one of the biggest refugee immigration in recent history.