YMMV / Agents of S.H.I.E.L.D. S6 E07 "Toldja"

• Genius Bonus: Jaco breathing fire doesn't completely come out of left field; presumably since he huffs chemicals such as bleach and other flammable compounds as his natural atmosphere, his standard lung capacity would be too high to allow him to ignite the gas; but given enough time away to replace the chemicals with Terran air (20% oxygen) he can get himself into the combustible range. Also note how his breath is visible when he awakes, similar to breathing fog in cold weather.
• Narm: Jaco's face when breathing fire looks extremely goofy.