An oratorio is a large-scale piece of music for choir, orchestra and vocal soloists, which tells a story without staging or costumes. Most oratorios are based on stories from the Bible, a source that Handel's English audiences knew well.
Enthir is a Bosmer sorcerer and merchant found at the College of Winterhold, and has connections to the Thieves Guild in Skyrim.
Besides, I'll be honest here, I liked Skyrim's story over Oblivion's. In Oblivion, you're a glorified errand boy. Sure, you're the Hero of Kvatch, the Champion of Cyrodiil, the destroyer of Oblivion Gates, but you're not the focus of the story, Martin is.