One of Newt's creatures gets the magical equivalent of rabies. He keeps insisting he'll find a cure, even as the creature becomes more violent.

Eventually it attacks and badly wounds Graves. Newt realizes the creature has to be put down.

I'd prefer if Graves is sympathetic-- although he's not happy it took him getting ravaged for Newt to see sense, he understands that Newt is very close with all his creatures and that this is painfully hard for Newt.