I'm currently trying to find a manhwa I lost due to the "list loss" this January.
Main character had long grey hair he kept braided. He had a scar on his forehead from childhood when he was hit on the head and he lost empathy with people due to it. His mother tried to raise him despite his brain damage changes and was successful for the most part.
His mom was murdered by the #1 hunter-type (different power system from hunter stories but best way I can describe it). The MC goes back in time and ends up joining the same team as the #1 when he was a teenager.
Loyal to bingsoo translations too! I will not click on a translation made by another group trying to snipe this manhwa.