Some of Rukis' characters, with lighter fur, burn it to create darker-coloured patterns. Which is an idea I nicked for characters with lighter fur.

My characters have a few options, restricted to their setting: Body paint for temporary marks, dye for more permanent solutions, and bleaching with the use of crushed limestone.

Often the skin colors beneath an animal's fur correlate to fur color patterns. What if tattooing the skin caused the fur growing from that part of the skin to take on the pigment of the tattoo?

It does not, though c: that'd be so easy, but that isn't how this works, unfortunately.

Ah, I thought ideas here were deeper into fantasy territory. What if similar concept, but the tattooing process was changed to target hair follicles and the ink/pigment/chemical used permanently changed how that individually affected hair follicle would color the hairs it would grow.

Ohhh, yeah. Fantasy van really be anything, tbf, going for spells, etc.
I should've clarified that I'm curious about how this would've worked in real world. As real as the one with anthro animals can be, that is c:

I play around with the idea of permanent dyes or even trimming down the fur before dyeing the area that's desired.

Some of my characters intricately paint on their tattoos, which has to be reapplied when it fades or the fur falls out.

But.... I have a sci fi world, so technology in my headworld gives another option: Bioengineering hair follicles to grow a certain color.

The equivalent of plot armour but for hairs. We just need a proper name for it.