It happened to be that Lucas had been inside that same dark room before Felix.
He had also gotten caught trying to run away and asking other children for help. He was also pushed inside the same way, but Lucas was more active than Felix since he did not get beaten up.
Lucas had been very attentive and immediately had caught the situation. He had cornered himself and sat in a corner in silence, trying his best not to even let his breathing make a sound.
His attempts saved him.
That person inside who Lucas didn't catch the sight of, lost track of him and eventually forgot someone was there.
It became that easy for Lucas to protect himself for the time being.
Then, Felix was pushed there.
Unfortunately for him, it didn't end well.
Felix was nervous, groaning in pain and his heavy breathing could reach the ears of Lucas who was in a far away corner of the room.