This mod changes the Bandit Chief in Mistwatch tower into a follower and a unique NPC rather than a generic dungeon boss bandit, changing her displayed name in the process. I was looking for something like this but it's not covered by WARP (yet) and the other mods I've seen have some issues so I made one from scratch.
Important information regarding this mod:
Do NOT marry her if you don't own a house. She has no residence and attempting to live with her at her home will result in her disappearance and a miscellaneous quest you can't complete being added to your journal.
I did not change her importance, this means she can and will DIE IN COMBAT unless you use a follower mod or some other NPC editor (or even the creation kit if you like) to change her to essential or protected. I recommend using EFF but AFT should serve the same purpose.
Less important information regarding this mod:
There are minor spoilers involved, if you care about a minor plot twist being spoiled and haven't played through Mistwatch before I recommend you save, clear it, then install this and play from the save you made before clearing Mistwatch.
Mods Used in Screenshots:
The Eyes of Beauty
Superior Lore Friendly Hair
Amidianborn Book of Silence
Skyrim Flora Overhaul
Realistic Lighting Overhaul
I tested this for about a day so I by no means know all possible issues this could have, Skyrim is an inherently buggy game and I've seen some unexpected and occasionally unexplained things happen. I can tell you everything I have tested (dialogue, marriage, combat and dismissal) works and she should be waiting in the top room of Mistwatch following dismissal if you don't set somewhere else as her home.
Alright I've been kind about spoilers so far but here goes the official SPOILER ALERT, the boss of Mistwatch is involved in the quest "Forgetting about Fjola" as the primary subject, the supposedly kidnapped wife of the quest giver. So yeah, she's Fjola and the situation can be resolved peacefully with her saying she owes you. I thought this would be a nice way for Bethesda to make another follower but for whatever reason that didn't happen, so I did it myself.
If you want to argue about how reasonable it is for the Dragonborn to be pals with a bandit kidnapper make a post and I will happily discuss it with you when I have the time. I will say in advance that there is a note in Mistwatch where the bandits seem to think she will be very angry when she finds out one of the prisoners has been beaten to death. This suggests to me she runs her ransom racket as a business rather than to satisfy some appetite for violence. That doesn't make it much better but it does make it different. I will also say not everyone plays the Dragonborn as a noble hero, and some people's player characters may be even worse than Fjola.