Saw a post saying that Cassandra Cain would hate Jason Todd and I'm sorry but. Are we talking about the same Cass Cain? Are we?
I understand the sentiment of "Cass would be outraged by Jason's morals" (when we're talking New Earth, at least,) that makes sense. I do think she would hate his ideals. Not Jason himself, though.
Cassandra knows death. Literally the thing that motivates her to be a hero is that, because of her ability to read body language, she experienced death after her first kill. She didn't just watch that man die, she died with him. She knows exactly what Jason felt like when he died, she knows how much it fundamentally changes somebody. I think she wouldn't understand how Jason changed for the worse, but she, out of everyone in the Bats, would actually, genuinely be able to see the boy Jason used to be when looking at Red Hood without separating Hood and Robin in her mind. Your death isn't something you ever forget.
Also, not only does she know the pain Jason went through when he died, she knows the grief Bruce went through, and is still going through when she finds out about Jason's death.
Obviously, everyone loves this scene (Batgirl (2000) #7) because it perfectly encapsulates both Cass' and Bruce's ideas of what makes a vigilante/hero. But there's a second layer to this, which is that Cass, who speaks in body language, feels Bruce's grief. In this scene, Cass isn't just shocked to learn that a Robin died, she's mourning Jason just as much as Bruce is. She can feel all of his regrets, all of his pain, all of his guilt. Cassandra would never be able to look at Red Hood without remembering what Bruce felt, what she felt, when he died.
Lastly, while Cass' morals aren't as much about "second chances" as Bruce's morals are, she is still desperate to save people. And Jason's main thing is that Bruce (and Dick, I'll make a meta post about Brothers in Blood at some point) can't save him. Saving Jason Todd goes directly against Bruce and Cassandra's morals, but another thing that Bruce and Cass have in common is how unwilling they are to give up. Everybody will be saved, or they'll both die trying to make it so. "Everybody" includes Jason, who's always worn his heart on his sleeve, who most likely wouldn't even try to hide his emotions/body language from Cass, because he never bothers to hide his pain, is always begging to be saved, just in a way that Batman can't fix. Jason doesn't just need help, he wants it. So Cass would never hate him, because she sees that Jason wants to be fixed, wants to change the man that he is, but feels like he can't do that until Joker dies, as seen here:
(Urban Legends (2020) #6)
And I think Cass would see that and would do everything she could to save Jason from himself without killing Joker. She could never hate Jason, not when she so fundamentally understands him and his struggle to believe he could ever be a good person. She knows his guilt doesn't absolve him just like her guilt doesn't absolve her, but Bruce gave her a chance to be a hero when he saw that she'd changed, became a better person. And I think she would go her entire life trying to give Jason the chance to change, too.