Hirelings are 0-level NPCs. Most hirelings (and expert hirelings) are low-salary, paid only a few gp 2-4 gp / month. Hirelings don’t count against the Charisma limit for henchmen. As PCs level, standard hirelings become VERY vulnerable because, by the book, 0-level characters can’t gain levels.
A potential path to more durable minions is hiring henchmen. Yet replacing many hirelings (such as a ship’s crew) with henchmen gets expensive and … complicated. There’s a hiring process for henchmen. Henchmen cost 100 gp/month/level in addition to hiring bonus(es) and shares of treasure. Charisma limits prevent PCs from hiring henchmen for an entire ship’s crew, as a standard crew complement is beyond even the most charismatic of characters!
Standard hirelings appear inexpensive before remembering that hirelings recognize hazardous duty. Hirelings might serve as part of a trading ship’s crew for their usual salary, but sailing to a mysterious island (pirate island, etc.) counts as hazardous duty over a normal trading mission. Hazardous duty salaries are calculated per day instead of per month, spanning the salary gap between hirelings (2-4 gp/ month 0-level sailor or marine) and henchmen (level 1 is 100 gp / level / month + bonuses). The 0-level hireling sailor serving hazardous duty would be 60 gp / month .
Yet even hazard pay isn’t enough. As the party gains levels, the level-0 hirelings are placed at risk greater than any sane 0-level hireling would accept as a condition of continued employment.
Long-duration hirelings can also have a backstory within the party—the trusted porter or animal handler. In my case, the party not only acquired a ship’s crew worth of hirelings, but, having lost their crew to slavers, made heroic efforts to rescue them. It doesn’t make story sense to replace a trusted loyal crew only to hire henchmen.
So I’m taking a hybrid approach. If the PCs increase the monthly wage for hirelings (e.g., sailors and/or marines) to the base rate for henchmen, the hirelings function more like henchmen. That is to say, pay a hireling 100 gp/ month, and their Saving Throws and THAC0 will increase to 1st level. Pay a hireling 200 gp/month, and their HP will increase to 2nd level (2d8). Should the party reach 11th level, hirelings could advance to 3rd level, with increases in HP (3d8), THAC0, and Saving Throws.
PCs are limited in the level of henchman they can retain: at 6th level a PC can hire 2nd level henchmen, and at 11th level they can hire 3rd level henchmen. For this hybrid approach, the most the PCs can pay a “hireling/henchman” would be 200 gp / month for a party averaging 6th level, but less than 11th level. NPCs worth more than that wouldn’t work for the PCs; they’d seek work with even higher-level PCs since that would earn them a correspondingly larger share. The maximum number of these henchmen/hirelings should also be limited by the total party maximum number of henchmen permitted the entire party, minus the number of normal henchmen.
For individuality, the upgraded hirelings can be assigned a proficiency in addition to their core competency (e.g. sailor, archer, etc.), providing an additional sense of story without placing them in the direct spotlight. It also explains the ship’s carpenter and ship’s navigator.
For simplicity, this advancement path is available only to an entire group of hirelings (e.g., a ship’s crew), in order to keep stats uniform for management purposes. And once PCs start paying these henchlings as henchlings, they of course have to keep paying them that way.
-make hirelings more durable to correspond with party level
-make hirelings more useful to correspond with party level
-provide hirelings a somewhat logical progression path, without the burden of tracking XP
-Cause hirelings to have a more solid attachment to the story as a whole.