Marigold

Marigold is a leucistic hawk moth and a witch, initially made for a short fic in which Mothiva gets turned into a Zommoth (as in, the in-game boss. don't worry, she's fine). Located in the Ant Kingdom's Outskirts, she is a curious, cheerful, and scientific bug, experimenting to the utmost of her field - magic involving transmutation of the flesh.

The field she lacks in, of course, is morals.

Transmuting a bug properly needs test subjects - bugs to run through new formulas, test variations, see what happens with a new form of triggering a transformation into something else. What more convenient place to get those than by cornering a random bystander and seeing what happens once they've taken it for you?

Many bugs, of course, are not particularly happy about suddenly being transformed into, say, a shambling mass of flesh. Marigold isn't the most gifted, as far as self-defence goes, and combat brews are a bit of a waste of time - why fight your wayward experiments when you can get someone else to do it for you? Looking soft and innocent means that a potential bystander will be far more likely to believe her when she says that a beast attacked her, and depending on the form, any victim may simply lack the means to protest.

Up against one tiny, unarmed moth, it's clear who the aggressor must have been - and if you build a good enough reputation with the neighbors, even bugs who can still talk will find former friends and family siding against them. After a certain point, it's obvious they're not who they claim to be - it's all social engineering, anyways.

Of course, any research needs funding - the criminal elements of Bugaria especially have plenty of use for making a bug vanish without generating a body, and Marigold's brews are permanent, if the client doesn't specify otherwise. For a bit of pay, you can vanish nearly anyone you want - without that pesky guilt that comes from actually killing them! All at the small, small cost of funding a local business.

Marigold herself would not personally consider any of her actions to be immoral in any way, merely seeing herself as a professional. Of course she takes jobs to transmute people into horrible monsters, of course she experiments with increasingly dangerous substances, of course she sells to any bug who will pay enough for it - it's her job, after all, and she's very, very good at it.