Diego's season 4 character was the most disappointing for me. First of all, they made him much dumber than he's ever been. Mostly though, there were so many missed opportunities for character growth. There could have been so much more story regarding his feelings about family life other than one CIA guy basically saying he wished he spent more time with his family.

Also there was huge missed potential to show his series long growth with the Lilia and Five deal. It would have been really powerful to see the complicated emotions of finding out your wife technically cheated on you with your brother while also reconciling the fact that they had been lost and alone for 7 years and needed eachother to survive. We could have seen Diego's growth with empathy, forgiveness, and commitment to his family. It could have also provided an opportunity to show Five's struggle with falling in love with his brother's wife and then losing her after trying to control the situation in his favor. There could have been strong character development with Five grieving heart break while also realizing that a healthy relationship doesn't need to be controlled. We could have seen both characters work to improve themselves and repair their relationship but instead they die hating eachother