How about "Anchored to the (Land)" ? Minor, General (RoP:M 47). Something to do with the Standing Stones, or travel. He gets depressed when not there, unless he has something to remind him of the land. (Wanderlust is a Major Story, or I'd suggest that)
I'm not really clear on how many standing stones locations there are in France. I think Carnac is it, or at least is so famous that it drives out searches for others, easily. Now this would be a great virtue to flit about Europe, but they are difficult to get to and tend to be isolated from settled areas.
That is the virtue i'm least attached to. I'm trying to think of something that makes him unique that would cause his brother and his "masters" to think he is very dangerous. I'll think on it some more.
As an NPC I had given him invisible to magic
Dunno if it's available to non-tytalus, or even non-magi, but what about the Personna Virtue?
Given time, he might take the place of anyone in your vicinity, thus making his ennemies feel quite edgy.
If you want to go more mythic, give him a superpower from RoP:M, like the ability to turn intangible.
Or you might want to give him as large an agency as you want: Make him a great info-collector (and thus dangerous through blackmail)
I don't think the Virtue makes a lot of sense for a Redcap, honestly. The persona loses all protections a Magus of the Order enjoys.
It also does not match up well with his membership in the Gonards.
I'm still mulling it over. Invisible to magic would help only vs magi. If the "shadowy figure" is demonic it would do nothing. And vs a group of non-magi it would not help much.
Is your phone DYAC'ing Goliards? Need to add that word to your dictionary if he's a member. 
I read that as "Gonads." Had to do a double take.
Same here.
And me as Conards, bad ortograph for Connards (roughly translates as buggers, or assholes) 
So I've been thinking about this, and I can't see any reason why he couldn't hid from diabolic rituals. Those rituals are magic, just magic that has been tainted by Satan. I'd go so far as to say that this is any supernatural effect. Comments from the troupe?
Reading the Virtue description, it doesn't specify Hermetic magic. Granted, the examples it gives are Hermetic spells, but for the most part those are the only spells described that the vast majority of players would have access to. So, if it were up to me, I would say that the Virtue applies to Magic, Infernal, and Faerie magic. Possibly Divine, depending on the situation and how important it is that Divine magic find its target.
A priori, it depends.
Tainted magic, yes, it's still magic. Same thing for non-hermetic magic, this is still a power from the Magic Realm.
Infernal/Divine/Faerie power? Not so much, just as a DEO won't affect a dragon.
Yet, I can see a realm-specific version working for each realm (like an infernal power to be invisible to infernal powers).
Likewise, divine version could work against any of the 4 realm, infernal versions against any save divine. But this would still mean having "invisible to infernal powers (divine version)".
It is a major virtue. If it doesn't work against any supernatural effect (excepting Divine) then it's an extremely costly virtue. It also requires someone concentrate on each spell that targets them every round. It's not a free you can't hit me with magic virtue...
It is less about the virtue than what makes him a threat to the conspiracy. In invisible to magic just does not seem like it would cause great worry.
Depends on what the conspiracy is, though. Saruman was consumed by the One Ring, but if he got hold of it he would have attempted to resist Sauron taking it from him.
Blackmail and info then? Favors? Allies?
Knowledge is power, that sort of thing...
Blackmail is a smidge difficult, they're brothers, or at least foster brothers, and their father is still alive. Also, Renaud doesn't know about any conspiracy or shadowy figure, or that he's a threat, but the player does.
Thus my quandary. As an old comic book reader I think back on DCs Crisis on Infinite Earths series. In that series, the big epic universe threatening villain opening move is to capture the Flash. Not Superman or any other universe saving hero, but the Flash. We learn latter that the Flash was grabbed early because he could easily travel between universes and thus making him a threat to a universe destroying villian.