Now I am a bit confused... The victim here could be even Helmeppo...
If Garpo dies/badly injured, Coby evolves
If Helmeppo dies/badly injured, Coby evolves
If Prince Gruss dies/badly injured, Coby evolves
Coby is more like Sanji, a sentient being too kind, he will awaken something like him (not exoeskeleton of course but something related to this kind of people).
Take note both have their CoO too developed.