2. Long life
It was apparent that the long life of a demon, was something not many would understand. The days got boring, nothing but a repetitive task. Sesshoumaru was one that tried constantly to relieve himself of the normal day to day habits. Which would explain the how and why he began to follow his brother's Miko. Nothing she did was repetitive, everyday was something new. It intrigued him. Why was his half brother the one graced with the miko? Just because he didn't technically like humans, did not mean he did not want one like her. Perhaps he should just take her?