This is why Soldat is even here, and watching closely. They arch an elbow up to catch Rosinante in the small of his back and shove gently forward and to one side, to try and rebalance him or, if that's not possible, push him against the wall for support instead of back down the stairs. Rosi put up a fuss about being caught in a fall before, but Soldat is not wasting food today if they can help it.

Also, they'd really rather not be fallen on, which is what would happen if the guy continued his backward plunge. Sorry, Rosi.