Don't think I've ever seen a show where I haven't liked a single one of the characters.
Rose is annoying and entitled and she does not seem like she's mourning at all. The dialogue is awkward and uncreative.
Peter is supposed to be an agent and he's a complete pushover. He clearly had no training since he takes orders from Rose, a civilian, who's supposed to be under the protection of the white house and is literally strolling around as she wishes. Also Rose adopts Peter like a pseudo boyfriend after one meeting, it is all super weird.
The attempt at fleshing out the assassins and making them real people we sympathise with, is also half hearted.
At one point a grown man blames a child for the death of her sister because she should have been watching her. As if that wasn't his job, and like a 7 year old could have dragged a 5 year old out of a pool anyway.
It's a really badly written show unfortunately. A lot of the acting is also not great, but that could be because of the bad script.