The Fire Ixupi is an unseen Ixupi, since it was encountered in events prior to the game. One can only speculate on it's appearance.
Possible hiding spotsEdit
It is hard to determine where the Fire Ixupi might have hidden. The only clues to a possible hiding spot is that Beth's body is found in the power room. One might think she might have tried to start a fire, or lit a candle while down there. It is unsure.
Vessel locationEditThe vessel the Fire Ixupi was in can be found up at the top of the clock tower. Once openned, Beth's spirit is released. She does give some important information, but she also wonders what happened to Merrick.
Loose in the worldEdit
Given the devestating effect of fire, it would be hard to notice any death caused by the Fire Ixupi. The only other place the Fire Ixupi might hide is in lit candles, or any other controlled flame. This makes finding the Fire Ixupi very rare, and very dangerous.