It's all Natasha can do, giving a warning like this. It feels like it's not enough but that's a familiar feeling for one of the more Ordinary Avengers (formerly, a bitter thought reminds her even now). If she said nothing she'd be complicit in whatever schemes Loki could ask of an immortal Artificial Life Form programmed specifically for murder. Sure, she's out there doing that murdering on the big bads of her own universe, but it doesn't change what she is.

Natasha knows because she's similar, if only mortal and human. Her entire upbringing was one nurtured programming for murder. She's still the most apt to resort to lethal force out of anyone in her team. It's hard to change what you are.

"You didn't know. Don't beat yourself up for something that's already been done. We just have to see that the fallout of this is as benign as possible."