Big Dong Zhongli's feed

Big Dong Zhongli created a topic of Backlight

I stopped reading in the middle to let it marinate
Spoil me please
Does the ML already knows what happened to our MC in the past? And what his step brother did to him? And his mother covered it up (iirc)? Is he still being a jerk to mc as well?? Was the 1st chapter happened yet? Where mc ran under the rain?