Best part was the vindication of Snape! I TOLD my nieces & nephews that he couldn’t be evil (a litte mean, perhaps)
LOL
My daughter just came in after she finished and got on my case about being right about Snape.
Depends upon your definition of evil, I suppose. He betrayed his chosen leader for personal greed. He didn't do what I demanded, therefore I will work against him. He had no trouble with children and adults being murdered so long as it wasn't the woman he had taken a fancy to and been rebuffed by.
I see an explanation for his betrayal, not that he was 'good' inside. He did it for his own self satisfaction, not because it was the right thing to do.