Doctor Francisia Monahan is an English Spark, who evidently specializes in biological sciences, specifically working with rats. (Though we eventually learn she studies other things, too...) She is a red-haired woman who normally wears a full face protective mask with goggles and a mouthpiece. Sheto deal with any new hazardous conditions she may end up facing.
Monahan's name is first mentioned (not counting The Works, see below) as Gilgamesh Wulfenbach Tarvek Sturmvoraus’s inoculation draught. To wit, distillation of Monahan's venefirous mus elixir is an ingredient required.
Later, when Gil and Tarvek view the string of recordings made by the Agatha-constructed Wingbot recovered from the lab of Lord Snackleford in the Londinium dome of the Queen's Society, the last of them Doctor Monahan taking possession of the little clank from a fellow British citizen/agent. She evidently is the one who delivered it to the dome filled with disloyal cultists, with Queen Albia never getting any word of the clank's message. When shown the recording, Trelawney Thorpe the Doctor's identity, adding that she has been officially missing for some time, and that she was a friend of Lucrezia's when the latter woman was in school.
When Ariadne Steelgarter we are informed that Monahan is holed up on an island somewhere sort of near Londinium and still working with her Horrible Rats. Furthermore, they are both acquainted with the rogue Smoke Knight Madwa Korel.
First Actual Appearance
Monahan finally appearswhen the comic's action moves to said island, where she is indeed scheming against Our Heroes with Steelgarter and Korel. Along with rats, she is an enthusiast of large bladed weapons, but to her disappointment, she doesn't get to immediately indulge in their use when Agatha and Co. fake their own deaths in an airship explosion.
She assists the also-present clank-copy of Lucrezia in getting the island's resident Mirror (sort of) connected to the one in the Royal Collection of Inconvenient Oddities, and she, Steelgarter and Lucrezia visit the where she creates her Rats. While her mask(s) make confirmation difficult, during all of this she comes across as surprisingly calm and pragmatic for a Spark. She's also pretty insightful, at one point to Steelgarter and Hippocrates Brunel that Lucrezia is atypically sharing large swaths of information with them because she (Lucrezia) thinks that she will soon have no further use for them and intends to destroy them all. And sure enough, when events reach the point that Lucrezia needs a biological Spark body to occupy, she immediately to copy herself into Monahan's brain with a built-in Summoning Engine, only to learn that Monahan has spent time working with the still-mysterious Loremistress Milvistle and has become an expert in Lucrezia's work... and so is able to block the attempt. She's also strong enough, thanks to her lifelong cheerleading enthusiasm, to kick the Lucrezia-clank into the nearby pool of Dyne-like water. She then finally removes her mask, revealing an attractive freckled face with one purple and one orange eye (both glowing), perhaps indicating that she is already making her own progression towards Queenhood. Speaking of which, she immediately proceeds to step into a shower of the Dyne-water and tell witness Steelgarter that she might want to run.
Steelgarter does indeed leg it while LuBot reappears and battles with Monahan, the two of them ending up "sharing" the available dose of Queen-inducing energy and both at least temporarily ascending as the island begins to collapse around them.
Doctor Monahan (no first name given) first appears as a character in the original 2001 version of The Works, looking much as she does in the comic.
Dr. Monahan herself is shown — rat in one hand, syringe in the other — with details Mad, Villain, and Spark.
Dr. Monahan’s Rats is another card (with two copies); details are Mad, Giant, and Pests. The two rats are several meters tall.
Finally, Dr. Monahan’s Diabolical Rat Stretching Engine has the detail Machine. It isn't worth any points itself (which is unique), but increases the value of Pest cards for one turn. So far the Engine has not appeared in the comic, the Rats instead being made Horrible via large glass tanks.
Theories and Speculations
Possibly relevant outside information
It's likely that the doctor was named after the Foglios' real life friend, Carol Monahan., and business associate