Elijah
We have our differences and usually, I'd care less.
But she's where I was a few years ago but with a less supportive partner. No offence but if you loved her, you'd stop your family being jerks to her.
I nearly ruined Sam's life and lied to Dean about being able to save him from hell. And yet once Sam believed I really wanted to change, once I started to prove it. He'd defend me to the end. Even to his brother, to everyone and anyone.
I'm helping Katherine because leech or not, she deserves a chance to be judged on what she's doing now. And that'll never happen if someone doesn't give her that first chance. And since its not her boyfriend, might as well be the demon that despises your family and their hypocracy.