What if an angel fell by mistake?

"How does your mind work?"

I was asked this question at a book signing when the first volume ("Lucifer's Flood") of "The Reluctant Demon Diaries" was released a couple of years ago. I would soon learn that readers were both captivated and conflicted with the idea that an angel could have fallen by mistake with Lucifer as a result of having been standing in the wrong place when the war broke out in Heaven. He is so embarrassed by his plight that he refuses to reveal his name even as he keeps a detailed diary of the drama unfolding on the Earth between mankind, Satan and God.

"No name" (the angel) is awkward, a bit of a hypochondriac and a bundle of nerves who is sentenced to serve as a watcher for Satan while all the time secretly working on a legal brief to present before the court of heaven as a petition for his vindication and reinstatement to the angelic realm. The conflict for the readers begins when they realizes how much they have in common with the misfit demon. Christian readers particularly are uncomfortable with the idea of empathy with a demon.
What do you think? Could a fallen angel be redeemed?