Could be water, could be growth, or possibly ice.
ice
The opposite of somebody who loves fire is somebody who hates fire. The opposite could also be somebody who is scared of fire. Fire is dangerous and hard to control, so many people are scared of it or dislike it.
water
The opposite of a plant can be several things. A balloon is the opposite of a plant as it is synthetic while a plant is natural. If you're thinking Pokemon then Fire and Ice are the opposite of plant as they are good against it. If you are looking at a plant on the other side of the room then YOU are opposite the plant. But in the end there is no opposite to a plant. The answer is most likely answer fire or light.
fire
The opposite of grass would typically be considered as something like pavement or concrete.
Life is the opposite of Death Fire is the opposite of Ice Myth is the opposite of Storm and Balance is exactly what the name implies, balanced, in the middle of all of them.
The opposite of ashes could be considered as something that is unburned or untouched by fire, like a fresh log or a thriving plant.
Aquaman. He can also talk to dolphins, unlike pyromaniacs.
The antonyms can be parch or dehydrate (quenching thirst). For a fire or other activities, the opposite can be start, inflame, or excite.
fire; dissolve; disband; remove; retire
The opposite of the word to chose is to deny, fire, refuse or reject. For example, you can chose someone for a job but the opposite would be to deny them for a job.
The opposite of flammable is inflammable, which means not capable of being easily set on fire.