When Ark is dominant in my personality, I will usually be either happy and content, or deep in depression. Some people might think it strange that I attribute joy and sorrow to the same part of my soul, but I don't see these two emotions as two different and incompatible feelings. I see them as the ends of the same line.
Ark normally comes to the surface when I am alone and reflecting on the state of my life. Sadly, Ark tends to come with depression more than joy, as I get depressed a lot more easily than I feel happy. (That doesn't mean I spend most of my time crying in my room, though. Being happy isn't that rare an occurence!)
The name "Ark" comes from an event from my childhood. I was generally a quiet and introverted person, but very occasionally I had to fight off bullies. The first time I had a fight, one of my classmates commented that I was "like the Ark in Indiana Jones - I looked innocent, but then I let all hell loose". The name just kind of stuck with me.