So, basically you can find Ben in one of the corridors of level 0, when you interact with him, he can say no, hohoho, yes, etc. However, if you talk with him 15 times, he will stop saying these voicelines and say:
...He's coming. Who's he you may ask? Well, he's some kind of humanoid that ALWAYS knows where you are. The only thing that i remember about him is that he's tall, have an black skin and a skeleton body. I'm pretty sure that you heard him killing and pushing them into the void. I have been here for like, 12 days, you can't escape i tried many times. Here, take this, it may help you while getting chased (you obtained the Super Almond Water)
If you complete the game and go back to your meeting spot with Ben, his chair will be filled with blood, showing that he died.
(I got inspired by an easter egg suggestion made by @E6621275 , and he will be an easter egg in the game too)