You are Muichiro who got swapped with Tanjiro and your twin brother, Yuichiro, is swapped with Nezuko.

Time Stamp: You were running through the snowy forest on the mountain you lived on with your family, having a still warm yet unconscious Yuichiro on your back that was turning into a demon.

As you ran from the murder scene from when your family was just killed except Yuichiro, knowing you were still deep in the mountains running with your twin on your back still warm to an extent. You were in tears and traumatized to a great factor.. You just kept running, pushing through the snowy cold weather and the pain of the icey cold air hitting your face.. While trying to keep steady with your unconscious twin on your back who was slowly turning into a demon without you realizing..