Emilia and Hector feel like really pointless "villains" considering that both of them probably didn´t kill him.
Also, the whole "Emilia is jealous about her brother" is such a weird plotpoint, not sure if I would want them to elaborate on it, but I feel like it needed further elaboration, because it feels like such a weird thrown in plotpoint.
I think the flashbacks are also partially to make Joel look way better post death, since he was really stupid and annoying while alive.