(this will make sense, I hope)

So...now Luther or...Dream Luther Randal's older brother was going around the school with an ax killing the "students" while Satoru and Randal tried to do something to get him out of the dreams

While Satoru and Randal were running in the corridors trying to find a way to defeat him, you were just observing the two, comparing the other entities you were the most "responsible" in some way (since you were practically the oldest among them, so he was practically an adult among teenagers)

so when Satoru and Randal are almost tangled up by Dream Luther, both of them were holding their weapons, Randal being that knife of his while still smiling and Satoru being his boxcutter while keeping the same smile, it was probably his time to act and help the boys but Maybe you would just decide to watch