Even the distance between the two of them had remained as they talked, as if Derrick had been unable to let Stephan get too close to him out of fear that he would suddenly be betrayed.
If he let his guard down, then it would be far too easy to do him enough harm once Stephan got close enough to him.
They were already in an enclosed space together, so it would be quite simple for him to be taken down there and to suddenly disappear from the world, with it being covered up.
There were no other witnesses around, and the area had no cameras overlooking everywhere, so there were no traces of him being there.
The closed-off area made it even easier to hide his body until it could be dealt with, and it was not like anyone would come looking for him there.
Such a space could be seen as being safe from outsiders, but it could just as easily be seen as somewhere that could be used to make sure he never left.
