They literally HATE each other. To the point, that leaving them unsupervised will result in bloodspill. There are several reasons for it - Mimiko thinks he is nothing more than threat to the village, and Danzou doesn't like her high positions and respect she has among other shinobi. Many more should follow, but I would run out of place. Anyway, the fact that Mimiko knows
what lies under bandages isn't that much of a reason, since she doesn't held much respect for her clan and doesn't really feel conected to it anymore. Mimiko will never miss the chance of arguing with him, especially, when she knows she's right. And I wanted to edit her some fancy official outfit. Well, she has taste for some killer earrings XD. Original from that orange-haired
Root guy... I bet Mimiko looks a bit weird.