Something I don't think I've mentioned so far in Monitors is a character advancement scheme. This is for the very good reason that I wasn't at all sure I wanted one. I know it's traditional; at the same time, that tradition means including advancement in systems where honestly it doesn't necessarily make sense or add much.
For example, while I do enjoy getting (or, more often, listening to the YSDC lot getting) and rolling ticks in Call of Cthulhu, logically speaking it's often hard to explain why a character of 50+ has suddenly boosted the experiences of a lifetime by spending two days examining a haunted house. Hellcats and Hockeysticks includes an advancement mechanism that I like, but doesn't really need one at all - it seems very one-shot to me, and I'm also not sure what benefit to the game is supposed to accrue from advancement.
Games that benefit from advancement tend to be those featuring a clear progression, where you're fighting goblins with rusty knives at the start, and dragons at the end. The advancement creates a sense that you're moving from a puny weakling to a powerful warrior. Monitors is intended to be more of an iconic game, where you create a character more or less as you want them to be and they stay that way. In addition, I'm not particularly planning to have enormous disparities in the power of enemies. Oh, and the idea for equipment is that basically all weapons are more or less balanced against each other in various ways. So... traditional statline advancement isn't seeming like a great bet.
However! It occurred to me that, since this is very much an organisation-based game, it might be interesting to implement an organisational advancement system.
Climbing the Ladder
The idea I'm toying with is that you can (slowly) accumulate respect or prestige within the organisation itself. This might come in the form of promotion (which gives you additional authority), or a trusted reputation (which tends to get people onside). Reputation might spread outside, so that civilians or enemies who do some homework on you also know you're a force to be reckoned with.
What I'd probably do is simply have each point of, oh, Seniority and/or Reputation represent a die you can call in when you try to use those things in your favour. Each gets one use per mission, and they can only be used when it makes sense for those to provide an advantage. They might help you acquire resources, manipulate NPCs, get away with stuff or call in favours.
In theory, this would offer a way for characters to develop mechanically over time and produce a slight shift in the play experience, without having to buy into the idea that characters develop great expertise over the course of a short mission. It would avoid the PC/NPC discrepancies that can creep in with some advancement systems, where because PCs acquire new skills rapidly, they can end up better at everything than NPCs who've devoted decades to their profession.
It's also possible that these advances could create new complications for the PCs. Additional seniority gives you more strings to pull, but also gives you more responsibility; infractions of protocol are more serious, failures are more prominent, and you're more likely to be caught up in internal or external politics. A reputation might grease the wheels or give adversaries pause, but it might also inspire resentment, attract unwanted attention, or cause an enemy to throw the kitchen sink at you. This idea feels like something for a group to decide, rather than a hard mechanical system, and to be implemented with plot developments or NPC attitudes rather than numbers. That being said, I could possibly see the GM having a pool of dice equivalent to the party's rep/seniority that can be used (once apiece) whenever it might hinder them.
You'll notice this doesn't in any way offer the chance to improve skills. Indeed, no. However, it's not unreasonable for there to be some kind of skill variation between newbie Monitors and seasoned veterans.
It seems to me the best way to offer this, in a fairly simple system, would be to just offer three or four tiers of expertise, representing probably a decade of service apiece. When they feel it's time - or if they just want to run a game with more experienced characters - the group can agree to move to a new tier. Higher tiers would offer a slight increase in training, and additional extras like spells, enhancements or weird artifacts. At high tiers, and with increasing Seniority, characters might have a trainee in tow, or even be leading a group of Monitors each, rather than working together on a mission - although that would always be a possibility. Attributes would not change, and it could also be fun to offer some kind of battle-scars or mission history system, especially for people jumping into high tiers rather than working their way there. But that's some serious horse-carting there.