The reason Assad has been unjustly vilified is because Qatar wants a natural gas pipeline to run through the Arabian peninsula, through Jordan, through SYRIA, to Turkey. From Turkey, it can connect with existing pipelines to Europe, in order to supply Europe with natural gas.
This proposed pipeline would threaten Russia economically, as Russia currently supplies Europe with natural gas.
Syria and Russia are allies. Thus, Assad said “No” to the proposed Qatar-Turkey pipeline that would run through Syria.
Next thing you know, there’s an “uprising” in Syria, and Assad is public enemy number one.
And when it became clear that the American public did not want another war (potentially with Syria) and Putin diplomatically stymied potential U.S. aggression against Syria, “ISIS” suddenly pops up out of nowhere, with funding, arms, supplies, logistics, etc.
The U.S. hates that Russia supplies Europe with energy (natural gas). It’s U.S. policy to isolate and surround Russia.
Isolating Russia involves preventing, halting, or stopping the spread of Russia doing business past its borders as much as possible; particularly with Europe, which the U.S. regards as its turf. Russia’s natural gas supply to Europe has been a thorn in the U.S. side for some years now.