Are capers a substitute for pickles in a tartar sauce?
I love capers and add them to different foods when I think it suits it. I'd much rather eat tartar (not tarter) sauce with capers than pickles in it. But them I'm not a fan of tartar sauce (maybe because of the pickles).  If you add capers, rinse them first to remove excess salt,  pat water off between a paper towel  and chop finely. I think a tiny bit of finely grated raw garlic would suit it nicely. Let the flavours meld together in the fridge for a few hours too.