Fire behaves by creating an updraft as hot air and burning vapors rise, which is influenced by the heat radiated from the flames. In zero-gravity environments, flames take on different shapes due to the lack of rising air. The discussion touches on the implications of this behavior for rocket launches, suggesting that while hot air rebounds to the jets, the effect of convection is minimal compared to the thrust produced. The conversation also highlights the interplay between chemistry and physics in understanding fire dynamics. Overall, the unique properties of fire and thrust in varying gravitational conditions are intriguing to explore.