Sides of a Hero

A different take on the sides being various impulses/ways of thinking, and fusing together to form the different parts of Thomas' personality.

Virgil keeps his past to himself out of fear and guilt. He may be a main side now, but was that what he was meant to be? Virgil never told the others about his existence prior to becoming a side. Would they still trust him if they knew what he did and who his friends use to be?
Roman called them Dark Sides, but what are they really and how is Virgil connected to them?