How to make NPC non-recruitable for Blades?

[Anbeegod]

I'm making a follower who prefers staying alone instead of joining the Blades. I googled it and found nothing, hope someone here can help me out.

 

 

Edit: I added the condition " GetIsID  NPC's name  ==  0 " to all 3 Blades alias in the rebuild Blades quest. Hope it works.