Finding Nathaniel

Finding Nathaniel is a quest in Dragon Age 2, which can be started by talking to Delilah Howe

Walkthrough
When into Act 3, go towards the Chantry, there you will find Delilah Howe talk to her, and she will plead to you to find Nathaniel, who is lost in the deep roads. If you have Anders in your party, he will remember Nathaniel and jokingly says I hope he's found a sense of humour