I understand that Sebastian was searching his daughter, bu c'mon, wasn't Joseph basically his best friend? He just vanishes after the end of TEW1 and he goes: oh well, too bad for him...
Like, we only get on talk about it and only if we find his slide, I can understand him wanting to forget about Ruvik, but Joseph?
He cares more about other characters he finds in this game that his long lost parther...