I've got a character idea that I'm not sure how the core concept would work with the RAW.
She was apprenticed to a Magus about a year or so ago. He started to do the season to Open her Arts (p. 106, core rulebook), which is simply a season of teaching with no lab total (except for an InVi to try to preserve any Supernatural Abilities she may have had).
Unfortunately, the magus was killed in battle during that season (as was 3/4 of the covenant's magi), and was never able to finish Opening her Arts.
My theory is that this would be sufficient to damage (but not destroy) her Gift, and render her a Failed Apprentice (per the virtue, p. 42), with enough of the Gift to enable her to be rather useful in the lab, I think.
Does this theory hold water? Or would it take more than this (e.g. a botch or accident of some kind) to damage her Gift enough to render her a failed apprentice? Does the Opening of the Arts have to be completed in that one season, once the process has begun, or can someone else come in after a time and start over?
Also, would I also be correct in assuming that this would destroy any Supernatural abilities she may have had?
I'd probably assume that a reset and restart approach works, and that you need something more serious.
But I do not think there's any firm evidence in this direction...
It's not necessarily the case, but it's certainly possible, in my opinion.
Ultimately, you are walking rather uncharted territory here, for which there are no mechanical guidelines I'm aware of. Whatever suits you...
As far as I know, the current books do not define stuff for the failed apprentices, neither positively nor negatively. I find that to be a real pity, since a "damaged Gift" is an extremely cool concept IMO. It leaves it open for you to define if having second sight is enough for you to be considered "Gifted" and as such able to help in the lab. it might be it is enough, or it might be it is not. It is also impossible to design a (mythic) companion with limited spontaneous magic, for example, at least if you want him/her to be able to evolve his abilities.
In your case, do whatever fits your troupe's wishes, really It seems you have a story there, so go for it. If you want a failed apprentice and your troupe decides that you could catch up later and continue with the rite, just make the character enter twilight during the massacre in her covenant (so avoiding most of the mess) and return from the experience with a scarred Gift that cannot be developed any further. This is what I would be doing
FYI this just made me thoink about a character that is only partially Gifted, but that has a HIGH parma level and comunication, and acts as a teacher. IMS there are no books on Parma Magica (Rival Magic would tell you why, in the Amazon chapter) since the Order wants to keep the secret inside, but a failed apprentice that still has a high loyalty to the Order of Hermes and is a good teacher could be taught Parma, be accepted in Exmiscellanea and mad einto a really cool tracher. Maybe even a fairly competent semi-magical combatant. Food for thought, at least for me!