So we all know Dabi has a body made to deal with the cold, right? So that paired with his survival at that the peak and that weird glow in his chest have lead to a theory of mine, which is Dabi is using the excess heat in his body to burn hotter. Constantly cooling his body would allow him to survive the heat, and would account for the miracle of this garbage panda-hot topic fusion to have survived this long with his lack of self preservation instincts. Just my theory, though.