Folks often make fun of the fact that Ernest says "my brother" instead of "our brother" during the Frankensteins' reunion after William's death as if throwing shade at Victor but like
There's some 10-ish years age gap between Ernest and William, for Victor and William it's 17. William was most likely not even a year old when Victor left to university and there's been radio silence from him ever since. Victor and William literally don't know each other, for pretty much William's whole life Ernest has been his only brother. It was just the two of them and Liz, Victor was never part of it. So it's natural that Ernest would slip like that.
Victor lost the idea of a brother but Ernest actually lost a brother
proposition: boy valentine