Might sound like a weird question, so here's a bit of context:
The story I'm writing is quite fantasy-driven (i.e. characters can seemingly "create" elements like thunder and water out of thin air). However, despite these fantasy elements, a lot of realistic moments occur which are often based in human unpredictability, so it's not like characters don't fear anything because they possess special powers or whatnot. Parts can easily turn into a killing/slaughter scenario a la "A Song of Ice and Fire", or even "Attack on Titan".
In a certain scene, an entire village was put up in flames. Amidst the confusion created by this, a man saves another fellow man from a house that is completely alit in flames. Upon his rescue, the half-burnt man asks his hero to save his daughter who's still in the house, to which he replies with the question: «How old is your daughter?». The other man is baffled by this response, not understanding where he's coming from, to which he backs up with «If your daughter is around 4 years old, there's nothing I can do».
My explanation is that this character is not risking his life if he knows the person-to-save would most likely die even after being rescued when other (possibly more important) lives are concurrently in danger. So my question is this: If a house is on fire, are young children more prone to faint since they have a more underdeveloped body system than adults, or, due to their size, can they stay safe from smoke and large fires by sticking themselves into corners until their rescue arrives?