I must have missed it before, from HoH: True Lineages, that Bonisagus and Trianoma had a son, who fled their cave in the Alps when he was only five years old. I'm thinking of using him in my campaign, or at least his descendants. What could have happened to this boy? Are there any "official word" about his story I might have missed, or hints in any of the 5th edition books?
Have anyone else used this in a campaign?
And as for the Mythic Blood virtue that his descendants have, any idea for powers to go with it?
If something defines Trianoma and bonisagus ("Papa Bonie", in our campaign) is unification. Political unification and magical unification of different magical traditions. Something along the lines of leadership, comprehension and a higher purpose could work here.
No problem at all with that "watering down". They are still descendants of Bonisagus and trianoma, and medieval legends do not take that watering down much into consideration. The 7th generation specially if it was a 7th son) would be extra-powerful for sure, for example, probably surpassing Bonisagus himself in some areas
Not all the generations need to have magical either. You can get a magus, then 3 generations that carry the magic in their veins but do not develop the Gift and then you get the magic rising again.
I can easily see a covenant spinning around this bloodline, secretly or openly depending on your particular saga. The boy fled, but he (or his descendants) might have been found and hoarded as a resource by a covenant. If it is for good (great unity of the Order, further knowledge and share it...) or ill (the opposite), is up to you
Or he might have been ripped apart by a pack of wolves and thus ends the bloodline
Bonisagus's son was mentioned in the orught drafts of SoI, but I think he was removed before the public draft. He was living for a time in Sion, where a cult had developed to preserve and benefit his bloodline.
What about the last descendant of this bloodline is the founder of the Children of Hermes, or maybe the immortal son of Bonnie and Tria himself ? An uncanny and exceedingly effective knack at mystery syncretism would fulfill the magical unification, the cult head is known to be very charismatic and the CoH are very missionary, which would fulfill the political unification.
If he fled when that age, he may never have realized his own full potential. A Mythic Blood-line could easily live in descendants completely ignorant of it's existence, for better or worse. Where does a 5 year old go? Unless already a natural Hedge Mage at that age and able to fend for himself, he gets adopted by a family, takes a new surname, and is lost to easy knowledge. No reason to expect that he is found and raised in the Hermetic tradition, or even that he becomes a hedge mage as he matures - especially if his powers center around Vim. No magic, no magic for Vim spells/powers to affect.
Also, if a descendant, no reason for there to be a family tradition - maybe it has been dormant for generations, maybe it skips a generation, maybe... whatever. A 5 year old is not likely to start a family tradition about it, especially if he's vague on the details himself.
If the Mythic Blood powers are subtle or related only to magic, or never recognized for what they are, they, too, could pass from generation to generation and never be of much note - how many spells does the typical townsfolk encounter? Almost any power related to Vim would be useless in most peasant life-styles, never activated nor called upon. Perhaps only in the presence of a Magus, or real magic, would a descendant have such manifest, and then they might not realize what it was unless they traded careful notes with others on what they saw or what is "usual".
And as a "civilian", the bloodline would get passed on in the usual way - quite a branch of the family tree, possibly. No reason to expect anyone to swig a Longevity Potion if you're not in the Hermetic Order.
I think a descendant (or a truly decrepit old hermit, if the original boy! How long ago???) who knew nothing of this truth but had a powerful and disturbing effect (MuVi?) on the PC's magic (consciously or not) could be a lot of fun. Paint him as a muleskinner or tracker, a rural type who the magi see only as a tool, and let them put together why their spells are off, and then why "s/he" is the one doing it. Not like they come with labels.