I just like From the Abyss and wanted to write something about it. Also, since I'm always worried about OOC, I'm probably not going to have much to do with the main cast, so I can write for fun. There'll be interactions with characters the original work didn't give much information about, as well as lots of original characters. You can basically treat this as an OC-focused story in the same world.
Theme: The journey itself is the greatest reward