Yarrow

Intelligent and caring with a secret craving for adventure and excitement, Yarrow was too careful and sheltered to do anything drastic on their own. They busied themself instead with the medical field, specifically patient care, with belief that helping others would be fulfilling enough to forget their own daydreams. It didn't take much convincing for them to join Grimm and ditch town for something new, in fact, they tagged along longer than Grimm would have liked (but that's not the issue it thought it would be).

After it ditched town for five years, Grimm finds Yarrow as the town doctor. He essentially works for free and asks only the people "pay what they can" in food, favors, or money; he's well-loved in the community. Yarrow and Grimm reconnect and a year and a half later, Grimm's past work catches up to both of them and Yarrow is kidnapped.

Over the course of a year, Yarrow endures genetic modification before Grimm hunts them back down. They're actually very okay with their new body, but it leaves them with a taste for revenge against the people who did this to them and countless others. They then make it their mission to blow these places up (with their partner's help).