This story is a sequel to the From the Shadows comic arc (51-53).
Shadowlock and Twilight parted on good terms, after a few clashes. But when he shows up again, asking for help in undoing the damage he caused, the two of them embark on an adventure that will change both their lives.
Immense thanks to Triq267 for prereading and consultation, as well as to the wonderful folks at /mlp/, where I posted the rough draft.
Note: I commissioned the cover art from PrinCrim.