There are many issues with permanent inks, especially on lighter colored furs, however what I've got here is very temporary, and something I picked up in my college courses - tailor's chalk.
Coming from a person who HATES the texture feel of run-of-the-mill sidewalk chalk or school chalk, I love this stuff! It has a very smooth surface, so it's not powdery or feels weird to hold. I'm pretty sure I had a red/pink chalk too but I must have hid it for safe keeping. This lot of 5 pieces I purchased on ebay for about $6 including shipping.
(Tailor's chalk also comes in a powder form that can be dispensed - my grandmother uses these, and the chalk comes out of the plastic tool using a wheel mechanism.)
These write on both light and dark fur that has a knit backing (DF fur does), and can be very vibrant depending on pressure. The chalk sticks long enough to mark pattern edges and labels, and rubs out easily, making a fantastic temporary marker during the suit building/sewing process, and especially for pieces marked wrong - simply rub your finger(s) against the fur backing to make the line lighter, and the new darker line replaces it so there aren't multiple, confusing lines or markings.
Left photo has fresh chalk marks, right has rubbed out marks.
Hope this helps anyone. c: