I would argue that Elektra killing Alexandra was hinted at earlier, we just need to look back to her punching Murakami going to attack Daredevil to realise that Elektra reacts badly to people threatening Him.
I would argue that Elektra killing Alexandra was hinted at earlier, we just need to look back to her punching Murakami going to attack Daredevil to realise that Elektra reacts badly to people threatening Him.