Yep, that could certainly work. We could simply state that the vis-saving applies as long as the Mercurian is the one leading the ritual, even when non-Mercurian join in using WC. Also, the Mercurian must also know the ritual being cast, or he cannot lead (and so cannot apply his vis-saving to the ritual).
The draft stats for Rufus the Cat, Petronius' Magical Animal Companion. I've used the basic template of a cat and adjusted to a Summer animal. So I only added some virtues and flaws, xps, as well as magical power. Note that Rufus is a wild cat, much more feral than a cat living near humans. As such he's just beginning to get used to humans and is still observing them from a safe perch, learning what he can. The reason why Rufus befriended Petronius is because he felt kinship over the human (affinity with portals), which explains why Rufus' main power is so close to Petronius' area of interest. I've also given Rufus some good, though short-term, powers to increase his fighting abilities. This seemed to make sense for a feral cat.
Note that although Petronius will eventually make Rufus his familiar, but that for the moment Rufus has not yet accepted this. Communication is still fairly basic between the two, as Petronius' ability to understand Rufus is limited. If someone wants to play Rufus during the stories, that might be fun.
I'm open to suggestions and changes.
(Edit 2: Moved the stats here)
I debated about this one, and decided to try it out, but I don't know enough detail about the Church in the area to really know if being a priest and a magus would be possible. Somewhere along the line, I was imagining the "itinerant friar" model. I'll think about it more ... anyone else have thoughts on this?
I'll probably go with never actually taking Holy Orders, having been "rescued" by the visiting magus.
The following HR was mentioned on the general board, and I figured this might be a possibility for this saga. Seems like a good balance between unchecked familiar progression and the RoP:M rules that cripple familiar advancement.
It's one of the better ones I've seen. My problem with the whole "magical creatures don't learn and live forever" is that I have a serious problem seeing any kind of motivation for a magical animal to become a familiar with those rules in place. Taken at its most strict a familiar with anything but minuscule might would never learn anything without eating vis. And would gain close to nothing on a "upgrade" from Magical Animal Companion to Familiar. Actually it would lose out on immortality (since a familiar typically dies closely after it's master) and give up some freedom (the bond).
And with those rules combined with the possibility (I seem to remember from somewhere) of a mundane familiar, that suddenly becomes a mechanically much better choice. No might, no learning restrictions -> much higher skill for helping and discussions.
Well, I'll have to take a look again if I want to skip a year (that is "do Hippocrates have some lab-work he would like to do") before I decide.
If we want it really simple we just drop the role-playing and book keeping 100% and let the familiar learn as a grog at 15 XP per year. It reduces book-keeping and optimizing quite nicely while still keeping familiars advancing steadily.
I've advanced my magus to 6 years PG. See the advancement log and his current stats. Not that as part of the advancement, he now has an active longevity ritual created by his pater.
Here is a version of Aedituus at Gauntlet. I still need to determine spells, and having recently received HoH:MC, and quickly read the Criamon chapter, I am leaning toward Aedituus following the Path of Walking Backwards, possibly reaching the first station before arriving at the Covenant.
Aedituus ex Criamon
Characteristics: Int +2, Per +1, Pre 0, Com +2, Str 0, Sta +1, Dex 0, Qik -1
Size: 0
Age: 33
Decrepitude: 0 (0)
Warping Score: 0 (0)
Confidence Score: 1 (3)
Personality Traits: Patient +1, Impulsive +2
Virtues and Flaws: The Gift, Hermetic Magus, The Enigma, Affinity with Magic Theory, Book Learner, Educated, Gentle Gift, Puissant Mentem, Second Sight, Sense Holiness and Unholiness Student of the Divine; Deficient Rego, Noncombatant, Pious, Visions, Vow (of celibacy), Weird Magic
Abilities: Britain Lore (History) +1, Awareness (alertness) +2, Charm (first impressions) +1, Chirurgy (setting bones) +1, Concentration (reading) +3, Folk Ken (clergy) +2, Guile (lying to authority) +1, French (slang) +2, Church Lore (politics) +2, Profession: Scribe (neat work) +4, Teaching (Latin) +2, Artes Liberales (ceremonial magic) +3, Latin (Hermetic usage) +5, Medicine (physician) +1, Theology (heresy) +2, Code of Hermes (mundane relations) +1, Dominion Lore (saints) +2, Enigmatic Wisdom +1, Criamon Lore (personalities) +1, Magic Theory (Creo) +5, Parma Magica (Mentem) +1, Penetration (Mentem) +2, Second Sight (ghosts) +1, Sense Holiness/Unholiness (good) +2.
Arts: Cr 8, In 2, Mu 2, Pe 2, Re 2, An 0, Aq 0, Au 1, Co 7, He 3, Ig 0, Im 3, Me 7, Te 0, Vi 3
Character Concept: Abelard was the fifth son of a wealthy land owner in England. His mother died while giving birth to him, and his father donated a large sum of money, along with Abelard, to a local monastery, in exchange for prayers said for his beloved wife. Born with a birthmark on his left side, Abelard was always a strange child, and not always trusted by the monks, as he sometimes seemed to know what they were thinking. Most tolerated him however, and at the age of 18, Abelard was on the verge of taking Holy Orders. He had been hopign this would ease his sense of loneliness, even among the monks of the order, but his spirit still felt the need for something else as his ordination day approached. When a wandering scholar stopped at the monastery, he asked if Abelard might join his entourage, and provided the monastery with a generous donation in exchange for the young man. The Jerbiton magus recognized the Gift in the young monk, but not being in need or desire for an apprentice, paid off a debt to a Criamon maga with the gift of an apprentice. The maga was careful to try to preserve her apprentice's supernatural abilities upon opening his Arts, recognizing their value for a Criamon. She was never able to completely distract him from his monastic vows, and gifted him with the name Aedituus at his gauntlet. Aedituus continues to shave his head in a tonsure, and dresses in plain black robes, cinched with a white rope belt. He has been following the Winding Path since his gauntlet, and seeks to develop ideas about the relationship between the Enigma and the Divine.
EDIT: changed ability from Civil and Canon Law to Medicine, and swapped Au and He scores.
I'd like to stack Regiones in there with Aurae in the same minor focus - still fairly narrow I think.
Objections?
Probably okay with me. I don't know enough about Hermetic Architecture to know the conseqeunces of this later on, but Aurae/Regiones seems to be a narrow field within Vim. Would the bonuses apply to rolls for spells directly affecting/detecting only, or are you thinking more broadly?
Background for Aedituus: pre-apprenticeship
As the Abbot intoned the prayers of consecration in his dry and barren voice, twelve-year-old Abelard found himself, as usual, starting to drowse. The coolness of the dim stone chapel was so much more comfortable than the boys’ dormitory up under the eaves on the south side of the monastery, and the light that always seemed to surround Father Aelfric during mass was more comforting than disturbing. The sleep lost to last night’s prayers snuck up on Abelard. John, a year older, started whispering about how hungry he was, and how he wished for some of his mother’s stewed lamb with rosemary. Several of the other boys also whispered about mundane activities, and Abelard startled awake when he began to taste the savoury stew that John imagined. He opened his eyes, and as the others fell silent, all apparently paying studious attention to the mass. Abelard wondered that Brother Joseph had not waded into the whispering boys to pull some out by their ears, but the older Brother remained off to the side, apparently and surprisingly oblivious to the transgressions.
Later, as Abelard and John ate together, the thin gruel barely enough to break the night’s fast, Abelard whispered, as talking at meals was not really allowed, “Nothin’ like your mum’s lamby stew, is it?” John raised his eyebrows in apparent surprise, but said nothing until they were finished with the meal.
“How do you know about my mum’s stew?”
“You kept talkin’ about it at mass this morning. Made my mouth water to hear it!”
John stopped, and looked at the younger boy. “I didn’t say nothin’ at mass this morning! Besides, you were almost snoring; Brother Joseph is going to tan your hide if you keep falling asleep.”
“I only closed my eyes. You’re the one who’ll be in trouble for talking during mass.”
“I told you I wasn’t talking!” John punched Abelard on the arm.”
“You and everybody else had lots to say this morning. I was surprised Brother Joseph wasn’t red in the face.”
John gaped at him. “You must have been dreaming. Nobody talked during mass this morning, not even William after the whipping he got yesterday.”
Abelard thought for a minute. “Then how’d I know about the lamb stew?”
“I dunno.” John looked at Abelard quizzically. “But it is good, and you’re right; that slop at breakfast makes me miss it.”
As time went on, Abelard found he could sometimes hear what other monks were thinking, and that he could also sometimes project his thoughts toward others. The most unfortunate occurrence was during mass, a few weeks after the exchange with John, when Abelard had decided that Brother Joseph looked like one of the fat pigeons in the courtyard. Although he had said nothing (which was confirmed by John) Brother Joseph had apparently heard the remark, and reacted badly. Abelard found himself in the kitchens working off a serious penance for the next several weeks, and had to be very careful around Brother Joseph from then on. When he was fourteen, a bishop visited the abbey, putting everyone on edge, as he was known to be a hard man with a temper that seethed and burned. Abelard took an instant dislike to the man, and avoided him as much as possible. On the last day of the visit, the bishop said the mass, and Abelard found it odd that he did not glow as the priests of the abbey did when they raised the holy bread. When it was his turn to receive communion from the bishop, Abelard was overcome by a foul stench, and kneeling there with the host presented to him, vomited on the bishop’s slippers and passed into unconsciousness.
Abelard awoke in the infirmary, tended by Brother Matthew, the Infirmarer. Matthew was a little hesitant to approach the boy when he first woke because while Abelard was asleep, Matthew had sudden and pungently smelling visions of the bishop whenever he touched the boy to check his fever. As Abelard recovered, he told Matthew about the illuminated priests, about the ghosts that wandered outside the walls on All Hallow’s Eve, how he always enjoyed the smell of roses around the altar even during the winter, how he often knew what someone was thinking, and how he could sneak past Brother Joseph at night just by imagining the older man asleep. Worried that the fever had taken Abelard’s wits, Matthew had the boy assigned to the Infirmary where he could keep a closer eye on him. In addition to his morning and evening work in the scriptorium, Abelard enjoyed his afternoons in the Infirmary.
Abelard proved an able helper, learning the skills of an Infirmarer, and often seemed able to ease the pains of the older monks more effectively than Matthew could. Unfortunately, the episode with the bishop and his uncanny ability to know what others were thinking often put him at odds with his superiors, and Matthew found the Infirmary and herb garden to be places of refuge. At the age of sixteen, Abelard took the vows of a monk, and looked forward to being able to take Holy Orders when he turned eighteen, hoping to end his feelings of isolation and join the order fully. He continued his duties in the Infirmary, tending many who came for treatment, including the occasional traveller beset by bandits. One pair, a father and son, bore little resemblance to each other, but the elder, who always wore a red hat, frequently referred to the younger as “filius”. The young man had suffered a beating at the hands of some bandits, and although the father seemed unharmed, he was certainly shaken by the ordeal. He was some sort of messenger, and left his son to the monks’ care while he completed his mission. Abelard struck up a friendship with young Charles while he recuperated, and was surprised at his knowledge of Latin. Charles had some amazing stories to tell, and Abelard shared some of his experiences as well. When Charles’ father returned, he and his son left with the promise of returning to visit Abelard. One or the other did visit several times during the next year, and Abelard found himself looking forward to their visits, as his isolation from the other monks remained.
A few months before Abelard’s ordination, Charles arrived, now wearing a red cap himself, with a much older man named Johannes, who was a scholar and knew Latin very well. He seemed to know exactly how Abelard felt about himself and his surroundings, and was able to discuss the techniques Abelard had learned in the Infirmary. He also glowed like the priests did during mass, but unlike them, Johannes glowed all the time. The older man became a frequent visitor, and explained that he lived in what he called a covenant with other scholars. Abelard found himself wishing he could visit Johannes’ covenant, surprising himself with a wish that extended beyond the monastery’s walls. A month before he was to be ordained, Abelard found himself in front of the Abbot with Johannes, asking to be released from his monastic vows so he could study with Johannes’ covenant. The Abbot agreed, and Abelard followed Johannes to his new life.
I'm thinking detecting (which is usually trivial), and/or affecting aurae/regiones directly.
All effects I expect to see fall under this focus are within the Art of Vim.
I'm not looking for a bonus every time I am within an aura/regio 
I will be researching some fairly high level spells and probably creating items with very high levels (CrVi 99 is an example given in TMRE).
There's stuff to be done before then, but if I ever want to get that high, a focus would help a lot!
I would judge regiones to be included in a minor focus on Aurae. As you say the focus applies when you (try to) affect the aura, not when you're in it 
I think it is still pretty narrow.
As long as you stick to spells that affect the object of the focus, and don't receive a benefit because of being in the presence of the focus, which you've already stated.
As I draft out more of Aedituus' background during his apprenticeship, I am thinking I may need to change his specialties, and possibly the Deficient Rego flaw. I also noticed that Hippocrates has the same high Arts as Aedituus; it might be better if I add some diversity.
I'll work on him more, and possibly post a revision tomorrow.
Claiming the Focus Bonus ust because "I'm in an Aura, see!" is not my point.
I just want a little edge for the level 99 effects I hope to do with Hermetic Architecture, eventually
I have an idea for a companion character, but I'm having a bit of trouble trying to fit him into the rules.
The concept is that of a cooper (maker of barrels and other containers of wood) with slight magical powers (and possibly the latent ability for more). He would be able to craft barrels that are subtly better than mundane ones -- the wine within keeps better or even age into much better wines, the barrels themselves are sturdier and last longer, etc. This could go as far as to be much more obviously magical, like containers that keep food fresh for X times as long as normal ones, that gradually transform the content into something else, etc. This would be obviously non-hermetic (possibly breaking some of their limits) but much weaker in general.
This does not quite fit any of the virtues that I've found in the books I have. My initial thought was something like Craft Magic in HoH:S (p.131), but that virtue only allows the character to infuse items with a power they themselves have. Then there is Touched by (Realm) in C&G (p.71) which can create Wondrous Items, but these have to be designed for a specific person so don't fit with the goods a cooper would make (and the range of possible "powers" is too wide). Another possibility would be powers similar to those of an Elementalist from HMRE, which would be fine for liquids contained in the barrels, but not so much for the barrels themselves (mostly Herbam) or other types of contents like food (mostly Herbam and Animal).
I'd rather have the companion's power stem from the Magic realm, as Faerie powers don't appeal to me. Have any of you seen some Virtue that would fit this, or should we try to build a completely new one?
Focus power? Warding the barrels from vermin? This would be in conjunction with Craft Magic
Well, my understanding is that Focus power (from RoP:M) is for Magical Character (i.e. those with Magic Might). I was seing this companion as more a mundane with limited magical power -- a kind of hedge mage without the Gift.
Combining Craft Magic with a minor virtue could work, although it would be unusual because that this virtue can only be expressed through Craft Magic. And although the powers are rather weak, they could be developped to be somewhat varied, like low-level spells.
I'll reread stuff regarding the Elementalists in HMRE. Maybe that will help me figure something out. (Hmmm, elementalist power with Restrictioin that it works only through crafted items, maybe.)
Ok, I've checked HMRE, HoH:S and Ancient Magic looking for something that would fit my concept. The closest I come are the Gruagach Give + Blessings, or Mythic Herbalism, combined with some aspects of Craft Magic.
First avenue (from HMRE): adapted Give (major virtue) + Blessings (minor virtue) + Restriction (major flaw)
The "Blessings" work only on the containers themselves, what they contain, or those who consume the content (in ascending degrees of difficulty). Additional "Virtues" that affects liquids and stuff will be established.
Second avenue (from HoH:S): adapted Mythic Herbalism
Instead of creating unguents and poultice from plants, create containers that affects its contents over time. A table similar to the one for Mythic Herbalism is created with appropriate effects for the containers, and for the content. Imbuing an effect on the content so that it can be passed on those who use it is very difficult. The ability used is the identified Craft.
In both cases, the magic manifests through the crafted items. When affecting the content of the containers, the magic takes some time to transfer from the container to the content, proportionate to the level of the effect.
Does that seem workable? I know we mentioned Craft Magic, but I find it too wide in its applications and not flexible enough for a non-Gifted character.
I acquired HMRE tonight, try and look it over quickly and get back to you for concurrence.