Ok, so I have thought about this...
First off, we have the identifing of Monsters
Lore / Scholarship / Discipline < --- 3 Most Important Skills.
I thought about it in a recent campaign, I have a stunted High Elf of the Autumn Court, whom has Greater Glamours (BEST ABILITY EVER), who plays a 7 String Baroque Lute that has Incite Emotion on it.
But as I was playing, I started realizing to breach glamours and veils, and be semi immune to some of the nastier things in the night you need Discipline.
Give them Stunt's called Bloodline / Ancestry / Lineage / Birth right things of the sort.
Of course I think this will limit the character, here is what I think you might do, as a bonus, these bloodline abilities would be the same as scion powers. Thus bringing the mighty pure mortal down to a minor talent. However, via story method, you could portray your character as a lower lined Grimm, and gain the stunts and refresh of a pure mortal, At the time of the Grimm switch, you drop "your job." and pick up the family mantle.
The advantages of this, at least how I see it are like this.
- 1 Blood of the Grimm - You Gain +2 to the ability to pierce veils, glamours, or magic to see the true nature of supernaturals.
- 1 Grimm Awareness - You Gain +2 in Discipline Saves against Supernatrual Attacks
- 1 Grimm-oire - You Gain + 2 in Scholarship or Lore roles against the Supernatural
Bloodline Curse - Aspect Grimm's Curse - All intellegent supernatural creatures make a Lore Roll of 4 to see what you are. Once they see you as a grimm, your Deciet and Rapport score decreases by -2 in Social attacks.
The addition of any supernatural powers, or sponored magic of any kind, frees you from the affliction of your cursed blood, forever passing the Curse to the next in line.
I think you also need to take a few other stunts, like the Weapons Loading for enemies, such as you carry a bandalier of shotgun shells on your chest, after realizing your facing fae, you load the Iron buck shot, there by meeting the catch, but on odd supernatural creatures where the catch is lower the score would be higher, thats when your Grimm-oires might help turn the tide.
I think the character has a great bit of potential as not only a playable character but one of the scairest support characters in the game. Of course, at the begining of the game, the party would all roll against the Grimm's in the party to see the level of trust throught the game.
Also the Grimm's Contacts score, can only be used to contact other Grimm's or Mortals. I would make this specific.
But I think once you flesh out a power list and a few choice mortal stunts the character would be terrifiying.
;p
Hope this helps, and hope to hear some feedback on how I looked at it.