I don't believe an element has the capacity to be "evil", after all, it is a nonsentient, simole collection of subatomic particles.
Fluorine is highly dangerous in the elemental state, a pale yellow gas, a few ppb in air is detectable, and 50ppb is intolerable.
F2 is highly toxic, and will rapidly burn right through all but a very few materials, such as monel metal or high-end fluorinated hydrocarbons, it causes instant, and very severe burns, in addition, it forms HF on contact with water in body fluid, which dissolves bones from the inside out, causing hypercalcaemia and hypermagnesaemia, which are often fatal in cases of minor F2 poisoning.