It can work. Seekers are good characters for solo games. Redcaps are good characters for that approach as well.
However, seekers can search a lot of different thingds. What is your player interested in? What kind of legends? What kind of developments and powers? That can give you an idea pof what he wants, Egyptian Myths, CuChulain developments or the secrets of the old Norse gods. Or whatever 
"Tales of Mythic Europe" might contain a story for your character - depending on what exactly you/he need. Most of the work has been done (there are adventures in there, not just story seeds). It depends a lot on what your character is good at (fighting: the Viking, social interaction: loveboat, or helping the widow etc)
Your player might also need ingredients for some kind of labwork, maybe?
Just an idea that struck me with your situation:
If the seeker seeks out some sort of items and/or information that involves much travelling/adventuring in the local tribunal, and is willing to do any journaling you don't have time for, playing the solo adventure might let you both have a lot of fun detailing the tribunal.
I might actually suggest some of the old D&D/AD&D adventures involving finding parts of an old artifact. The Rod of Seven Parts (en.wikipedia.org/wiki/Rod_of_Seven_Parts) is a very nice idea which could be stolen and converted to Ars Magica. Make it an artifact of Verditius the Founder and let each part be hermetic and the combination and synergy bonuses be non-hermetic. ("Solves" any rules problems I haven't seen 
).
Then add some AM story:
Before making his famous rings talisman and before joining the Order the Great Smith (Verditius the Founder) had another talisman: A jewel encrusted apple. This golden apple held 6 precious stones and was a mighty focus for his magic. After he joined the Order the apple was given to Bonisagus for study, to better incorporate Verditius' unique skill with enchantment into the theory.
During the Schism War the apple was stolen and used to great damage by the Diedne. When they lost a cabal of 7 houses (at least Quesitores, Bonisagi and Verditus mages) dismantled the apple. Much to their surprise it still held considerable power in each part, so the 7 took one piece each and promised to keep it safe and hidden.
Now all you need is to add a Seeker (and possibly someone else who seeks the same) and start digging for the parts 
The nice part is you can get the solo adventure to go wherever you want (geograpically and style-wise), and you can keep the effects small but nice, with a possibility to do original research to get extra bonuses or let them come automatically if that fits.
And if you keep it all somewhat local you and do a good log you might get a very alive and good detailed setting for the restart of the saga when you all have more time. (Kids tend to give you more free time as they grow.)
Also not to forget is that you as SG might want to play your own character as a "supporting role".
Gulla -- Really cool idea! I will look into those modules.
After some discussion with the player over the weekend, we are discussing the option of going less "epic" with the storytelling, and maybe doing something on a more micro level: Playing an herbam/animal focussed mage who chooses seclusion in a forest just after gauntlet. Early adventures would be focussed on simply surviving in the elements, building a lab, etc. Both of us agreed that this would allow for less work on my stressed time schedule. I'm going to pull out "guardians of the forest" and see what I can pull from that.
Now, of course, I'm intrigued by this Verditious artifact concept though....
I have found that the idea of a proactive explorer mercere works well. You can easily have adventure and city adventures with minimal justification (well he is just there just then) so works well for those classical modules that you can find in spades in the net. More of an adventurer feel here.
The forest thing works well. Make sure to develop the forest path, sicne that brings a whole new dimension to playing a looner in the forest. And can develop to be as epic as you want it to be. Being an ally of a primal force of nature is always cool.
Xavi
I'm not sure what you mean, specifically. Are you referring to a Mystery, or specific Path in one of the houses? (Serf's Parma)
If we go with the Herbam Loner, the player is not sure yet what House the character will be from....
The forest path is a personal mystery that anyone can develop. Even UnGifted people can. There are quite a number of suggestions in GotF abiout what potential forest path developments you can take, but they are not the only ones according to the text. Basically you enter communion with the forst spirit and go around protecting the forest and becoming part of it over time. Quite cool idea for a forest loon, really. House is irrelevant
Cheers,
Xavi
Ancient magic is an entire book about things for seekers to seek.
Covenant mentions a collection of well things as alternative to books. I forgot the name ...was it realia?
You could let build him such a collection. With that you would be open for every type of story.
Salve
Widewitt
Just remembered: If he is going the Herbam route, there is LOADS of inspiration in the Herizon story in Legends of Hermes.
Xavi
Hello there!
if he is not set yet, he can go for the seeker and weird magics route as well. Why not a Hyperborean Hymnist (ancient Magic) on a mission to re-establish apollo as the supreme Spirit in this world of unbelievers? He can easily be justified as a shepherd in the Balkans that used to graze his sheep near the temple of thousand columns. he also happened to have hyperborean descent, so the spirits in the area took an interest in him and taught him Hyperborean Magic. Now he is out on a mission to place Apollo as the ruler of the spirit world, as it should be. That means recovering relics, punishing unbelievers, scouting areas, negotiating with spirits and re-sacralize places, as well as some gardening, singing to the sun and chasing pretty women.
Remember that you do NOT need to be gifted to learn Hyperborean magic, only that he will be more powerful if he is since he will not need to "pay" for his Hyperborean virtues, so will be more powrful.
A solo saga revolving around him travelling around searching for artifacts of the cult to apollo and dealing with spirits to put them in their place (below apollo), supernatural beings and (gawd!) the Order of Hermes might be a cool feature. Highly supernatural even if the non-supernatural stuff can be there as well. You can even make the earming of some of the Hyperborean Hymns mission-specific (ordeal, initiation). I can see him purifying Delphos in a grand spiritual ritual ceremony to realign it to Apollo fairly easily
Cheers,
Xavi
Thanks for all the thoughts everyone!
The player has decided to play a Loner Herbam mage. And so now I'll delve into GoF, which I haven't looked at in probably 3 years, and I have Legends of Hermes on order (thanks for the suggestion Xavi!)
He's toying with a fun concept:
"My current (rough and uncertain) character concept is of a Gifted child apprenticed to an unscrupulous mage, probably either Tytalus or Tremere. His parens was rumored (accurately) to take apprentices, give them just enough training to make them useful lab assistants, then fail to prepare them for their gauntlet so he could keep them around as long as possible (assuming that a failed gauntlet means back to the apprentice pool until the next year). Character X sees what's happening - possibly tipped off by a former student - and starts studying on his own, stealing texts from the library and reading them in secret, swiping a stray pawn of vis to study from, etc. Because he's just picking up what he can, his studies are limited in both scope and depth. However, he picks up enough theory and practice that he's able to pass his gauntlet, much to the surprise of his parens and indeed the rest of the tribunal representatives. Bitter at his parens' neglect and his perception of the tribunal's indifference, he choses to be entered into House Ex Miscellanea, packs his stuff and leaves."
This feels like a dead-on Tytalus parens to me, but I'll let the player do what he feels is best. I can see the Tytalus parens considering this situation as a challenge to the apprentice, to see if he can actually master his studies, despite poor training. At least, that's what he tells his Sodales to get them to go along with it....
This will be the player's first foray into 5th ed. (he's been playing 4th ed for 10 years now.) Should be fun.
I would go for a bonisagus for his former master. A tytañlus with a reputation for doing that is likely to get a visit from the Bonie godparents to see if the kiddo is doing well, and abducted if he ius not. A bonisagus can be an ass as well, but he cannot have his apprentice taken away.
I would give him A LOT of magic theory for an apprentice (something like 5 with a lab assistant specialty. Maybe puissant MT as well. And very little in the way of arts (stingy master FTW!). It would do well with a weird spell selection if he has been taking spells here and there. He will probably have a fairly high Regoscore, sicne moving things around is a fairly basic feature of magic that requires low imagination. Some intellego and small spells to go unnoticed by his master and steal stuff would be cool as well. Put him in the role of the mouse in a game of cat and mouse, with the master being the cat. Legerdmain, guile and survival jump to mind as basic skills. Stealth and awareness too. Think about rambo, just smarter and weaker physically (not necessarily, though). The lab is Vietnam and the Master is a CHarlie.
Go booby trap something.
Cheers,
Xavi
Good thoughts, especially on the Magic Theory. I don't want to dictate too much to the player, but will make some suggestions.
And Yeah, I know he's taking "Stingy Master."
The rest of his email to me:
"Stingy Master and Sheltered Upbringing seem like natural fits, along with Free Study and Secret Vis Supply. I figure his nature interest can be appropriately explained by Faerie Blood, Herbalism, Animal Ken and Way of the Forest, while his faerie blood leads to Small Frame and Susceptible to Divine (which further reinforces his desire to leave civilization behind).
I'd also considered Incomprehensible and Tormenting Master, but those kind of depend on your vision of the campaign. Book Learner also makes a great deal of sense and could make for a good story hook if he decides to reestablish contact in order to learn more. I'd also thought about Patron or Mentor, with some sympathetic mage taking an interest, despite X's hostility - but I would only do it if you're enthusiastic about using that to introduce story ideas."
Keep in mind he hasn't looked at 5th ed rules yet. This is going off the 4th ed just to get his ideas flowing. His 5th ed. rules are in the mail....
A small idea to build on the Bad Bonisagus idea:
If he chooses Mentor that could be his original Master. He could have started out somewhere OK and when he showed talent (and was usable as a lab slave/assistant) the Bad Bonisagus came knocking. That makes for a link into Heremtic society, and can be placed close or far away depending on how close you want the Order connection to be
I like it Gulla, makes a lot of sense.
For the first story arc I think I'm going to do something along the lines of the following:
The Forest Spirit was once mighty, but at some point in the past a chtonic cult of witches (or perhaps Diedne?) built an altar, and were performing blood sacrifices there. Eventually this ancient magic warped into something darker, and an infernal aura grew. A religious order came and did battle with the infernal forces, trapping them deep in a new Divine regio, sealed beneath the burial place of a martyred saint. A monestary was built on the site to guard the regio.
The Infernal and then Divine auras diminished the power of the Forest Spirit, but it has maintained it's magic nature. Perhaps there are a few ancient trees scattered around the periphery of the forest, around each is a grove with a slight magic aura? If this spirit can get someone -- the mage -- to remove the Divine saint's remains, the divine aura / regio will fade away, and the Forest Spirit will regain it's former Might.
Of course, once the mage removes the remains... the infernal spirit will be released also....
I'm thinking that the Monestary itself is empty. Perhaps the monks were all wiped out (viking raid? plague?) So the monestary is in ruins, but the regio is still in place. There can be a nice battle with Divine guardians, and/or spirits of the monks.
We start out slow, with the mage knowing of one magic grove because of the vis source. During one of the harvests, he has a vision, and starts to puzzle together what the Forest Spirit is trying to tell him. The mage will grow in power slowly, figure out a way to connect some of the groves maybe (one of the Forest Paths?), and then get powerful enough to do battle with the Divine forces.
I invite your thoughts!
Sounds like a very nice plan. If you set it in Rhine you have lots of possible forests where this could happen. The forest around Durenmar (and Dankmar) is also well suited and the great old forest of central and southern Germany has (IIRC) been canonically broken into several weaker forests. Rhine is also a very good place for the Bad Bonisagus to live. As long as he's producing research he'll probably have a solid political backing.
I like the idea of the three auras (Magic, Dominion and Infernal) battling it out. I might personally add faeries into the mess as well, ie by having some faerie courts in the outskirts of the forest know the history or some domesticated/wild/expelled faeries know or live stories about this.
This is using vague remembering of the actual rules:
If the original sacrifices caught the attention of a demon, they could have been twisted to give more vis/power/infernal favors for more suffering. That could give you one (or more) faeries living the "tortured victim" story encouraging suffering in the area.
The Saint could in much the same way instire/create faeries living the "Noble Sacrifice" and "Cleansing Power" stories encouraging cleaning it up.
So playing out the story you sketch could then get you involved in the two faerie-group's conflicting wishes for how this should resolve
If you go for the "battles" approach that Gulla says, you can easily adapt the viking raid in TOME to fit your story arc in a more divine-infernal approach. THey can be bandits. No need for a river, even if you can have plenty of them around as well. One option would be to adapt the monastery ruins to form the basis for a village that has developed since it was abandoned by the monks.
I like the "reconnecting the groves" idea Nice one.
TO make stuff more interesting I would NOT tell the player that the second aura to emerge is infernal (hermetics cannot detect it as such after all. Demons can masquerade as other things, so they might put forward an appearance of messed up angels/saints/monks. Maybe divine, maybe faerie. Or maybe he tries to convince your character that he is the actual forest spirit and the other one is just a faerie trying to take over his rightful domain. Now, if you could make some sacrifices to empower him...
Cheers,
Xavi
I have continued this thread in a new thread, here:
https://forum.atlas-games.com/t/resurrecting-the-forest-spirit/6669/1