Fabrico pens ARE permanent. Wash it, bleach it, whatever Fabric Pens will stay. They are made for this purpose, and come in LOTS of colors.
Lots of pens which are labeled permanent, are not. I learned that at a fabric inking class. The instructor had samples of many supposedly "permanent" pens and they don't hold up washing, but Fabrico pens do. They are made by Tsukineko.
See here:
http://www.tsukineko.com/store/cart....duct_list&c=49