What if witchers looked similer?
What if when witchers said they were brothers they meant it in blood?
So the mages lost the original witcher recipe and decided to use already successful witchers blood as a stabiliser. The witcher mutagen already changes there body on a fundamental level, eyes, metabolism, aging everything. So it’s not to far a leap to think it would change there appearance over time.
So, witcher bloodlines.
It can either be that the finder of the kid gives there blood, or one witcher for a batch of kids, or one ancient witcher who was the most successful who’s blood was used thousands of years after there death. But the witchers all look similar, like how children look like there parents, cousins look similar, how you can track a certain nose shape through the generations, but in witchers.
Different schools have different bloodlines but can still track where they split off from the original line. The original witchers stopping or giving all schools there blood so one doesn’t believe there the ‘original’ or better than the others.
This could lead to where someone in a group is believed to die so no-one gives blood. Or one witcher gives blood to them too show that they believe in the kid.
Eskel and Geralt being close because they were brought up together, but also because they carry the same shade of yellow eyes and seasonal allergies the same as their alchemy mentor.
Vesemir who stares at his face and tracks what is the same as his dead brothers to not forget what they looked like.
Lambert who cannot stand to see his reflection, only seeing his tormentors staring back.
Coën, who covers parts of his face and pretends that he can still talk to another Griffen.
Just. Witcher bloodlines being more literal.