Sometimes Padawans dont follow their masters views and strife ensues... this can lead to the Dark Side....
Fear Leads to Anger, Anger Leads to Hate, and Hate Leads to Suffering.....
I would definatly not consider u THE Dark Lord of the Sith, but more like a Dark Jedi that has learned the ways of the Light Side and choose to use both for ur own benefit, similar to a Jedi Mercinary....