The anger of the Doctor might have terrified anyone else but Bill had seen it before, seen it used for good, and seen it used to educate her. She was not afraid. Without a word, she stood - or perhaps it was more like she was suddenly just standing there having not actually moved. It was silent. Even when he hit her countertop, she was not afraid. Instead, she quietly moved towards him and reached to wrap him in a hug.
"I don't know all of his story but I can tell you he was trying... Just not in that form. His next regeneration makes actual progress even if she's kind of a bitch about it. I don't trust Missy, but... she was trying." Well, at least until they got together. Then she had regressed but the Doctor didn't need to know that. What he needed now was hope and she could give him that much.
But other than that, Bill didn't know what she could do. This Doctor was a mystery to her. A mystery and yet the same - it was hard to put into thoughts, nevermind words. And thank god, she wasn't trying to do words. He tried so hard with no reward in reach - only his death and that was hardly a reward for a man like him, that quiet end. Oh, there were those tears she'd been trying to avoid and the heartbreak she felt for him.