Hello, this is my first ever post on bay12, I am very excited as dwarf fortress has been apart of my life for well over a quarter of it.
Anyways, I always loved the world-building aspect of DF, for over a year now I've been making fort after fort in a save in preparation for the new adventure mode update for the steam version; the one I use the most now. However, I see that some suggestions could be made if they have not been made already which could contribute overall to a fort's prosperity and martial prowess. I was thinking of a system that would allow the introduction of mercenaries in the fort. Although there is a system which exists already which allows the introduction of smaller groups into the fortress who serve the same purpose as monster slayers, I think that having the ability to negotiate contracts and hire mercenary bands from across the map would be an interesting addition to DF.
The premise around this would be simple. Since there already exists many independent forts across a randomly generated map already, I think it should be possible to send messengers that you assign in your fort to visit these forts as a friendly diplomat. If your diplomat were to arrive at the fort without injury, they will return with a proposal by the mercenaries, who will then prompt you to either pay what they demand for a monthly/annual tribute (having coinage would definitely help in paying), or - like with elven diplomats when they intrude on your logging operations - have it automatically negotiated down by whoever has the authority to do so, ultimately lowering the monthly/annual tribute, with the risk of the band ultimately denying the negotiated offer. Of course, you would only be able to hire independent settlements outside the jurisdiction of civilizations, in my past experiences, these forts are numerous along the frontiers of these civilizations. Some outlaw camps could be discovered through rumors and from people visiting the fort, allowing you to send messengers to these locations.
Once payment is made, the mercenary band's fort location will fall under your fort's holding with a couple options to decide what to do with them. These options should represent raiding and supplementing the force you already have. Raiding is self-explanatory; for as long as your fort is willing to pay the mercenary band, they will send soldiers out to raid whatever threat is presented to your fort, that being a string of human settlements or a goblin fortress. These attacks will play out very similar to how normal battles are processed in world generation, although when the raid occurs, the player will be able to track the raid in legends mode easier as the description of the raid will be followed with a simple explanation such as
"The attackers, lavishly paid by the dwarven fortress Thumbstickers, are motivated to lay waste to this settlement as dogs of war."Mustering should be another option that is available for mercenary bands, this would be the option that allows for the hired band to travel to your fortresses location to act as a military squad under your direct command, functioning almost exactly like any regular military squad produced by the fortress. Of course you will have to provide them with a barracks and a place to sleep and store their weapons, preferably away from the general population as mercenary bands tend to attract the unsavory types of folk that would harass your fort. Under your command, they are able to join your military in raids and pillaging moves. They however cannot be used as an occupation force as once the contract is complete, they will disband from your fort and return to their own. Aside from that, they can be assigned to burrows, patrols, all those kinds of orders that don't involve training, as it would be redundant unless you intend to keep rehiring the same band for their perpetual skills.
Mercenaries that are housed in your fort will intermingle with your population as regular citizens, they will more often than not be fighting amongst themselves in brawls and tavern scuffles and more often than not, your fortress's people would eventually be involved. Perhaps a devious enough person could see an artifact in your fort's possession and take it amongst himself to raise him and his friends arms up to steal it, causing a fight to erupt within your own fort. Although not all encounters will end in bloodshed, perhaps a mercenary had taken a liking to one of the people in your fort, and decides to join your fort as a mercenary, serving as a long-term visitor just like the vanilla mercenary system functions.
Overall, this idea of mercenary bands sounds promising enough to me, but instinctive flairs should be considered for this feature as just having soldiers a fort could hire sounds a bit bland. Perhaps a system could be adopted where you could "stop" the flow of income that flows into the payment of mercenaries, prompting a decision to be made where the captain approaches your mayor or noble and proposes an ultimatum, which either forces you to forcefully continue payment, or else risk the mercenary band to forcefully leave your fort, killing and maiming anyone that comes in their way. This would be great, but I think this idea could be improved upon as I borrowed it from the Cossacks series and their diplomatic center.
I also think that bandits should be another, more cost-effective option, although I would say that cost-effective is a dubious thing to call this considering the risk of adopting bandits into your fort's army. First off, bandits can be hired just like the mercenaries, albeit with a more-cost effective price initially. These bandits are small in numbers, perhaps only under a dozen in numbers, and some might outright refuse to fight for your fort depending on their relations to you and your civilization. Once hired, they will only attack your enemies in raids, and inviting them to your fort would only result in questionable thoughts and more chances of sporadic fighting. Overall, bandits should be thought of as only a raid force that you can use as privateers. In a world where civilization is few and far in between, just like colonial America, this option would be a unique consideration. Perhaps in a fort where the value is low, bandits could return captured loot as annual tributes, bringing a single party member to drop off valuables taken from the year's raids.
TLDR: I introduce an idea which allows for your fort to hire mercenary bands which are already present in DF worldgen. They can be hired to raid or supplement your force and are paid annually by tribute for a set amount of years. Mercenaries act just like military squads and can even defect from their band to join your settlement, just like monster hunters. Outlaws can also be hired but are untrustworthy but could offer annual tribute from the year's raids
Overall, I hope this idea presents some thought, and if this idea was posted before, hopefully it adds to the already present conversation. I do not know much about the inner-workings of Dwarf Fortress, so most of what I've said here is speculative and not mindful of the limitations of the program.
Cheers