She was noble and pure, and symbolised by time, and the direction East. She believed that guarding the Tower was her entire reason for being, and her devotion and noble spirit made her an ideal guardian.
When the fighting broke out inside the Tower, Siel realized her fatal mistake and couldn't bear the shame. She used all her life energy to maintain the Aetheric Field so that the world wouldn't shatter completely during the Cataclysm. She and Israphel are the most famous Daevas to have been displaced.