Bronn killing Tyrion and Jamie? What a cheap twist

The Faceless Men do assassinations for hire, but there's a lot more to them than that. They offer painless euthanasia to the terminally ill too. Everyone's got bills to pay. All the work they do is to support their huge underground temple of faces. And they supposedly built the city of Braavos, there's still a lot viewers don't know about their organization and its overall goals.

When Sansa asked Littlefinger about them, he said he only knew them by reputation, they worshipped the god of death (his tone sounded like yikes, those guys!). Cersei has no moral compass whatsoever. Their reputation wouldn't be a deterrent. If she doesn't want to hire them it could be she simply doesn't trust them; either that, or I'm not sure the Faceless Men will contract to kill ten thousand of your enemies instead of one, which is the sort of thing Cersei needs.

Bronn is just an expendable asset she can afford to pay off. He can probably handle putting a crossbow bolt in someone's back, right? Most of the people up north are probably going to die anyway. So his services may not even be needed. I don't think he wants to hang around in King's Landing anymore, since Cersei has become even crazier than Joffrey. This hands him an excuse to take off without it looking suspicious. I think he's going to take the gold and then defect to the other side when he gets up there.