Sable helps maneuver him into a good support position. He's small and light, which helps a lot. She's small but strong, and has done this before. She very quickly guides him into the best way to work with her to get up the stairs so that there is virtually no strain on any part of his body except his arms and shoulders, which he'd need to use to hold on to her and to help with balance and leverage against the railing. They manage it relatively quickly. Sable helps Cass to his room and waits while he finds his drawings. She takes them, promising not to crease or drop or bend them, and helps him back down perhaps with even greater ease.
Being more or less in full-out Nurse Sable mode, she helps him to the kitchen and sits him down with his drawings and whatever else he needs and puts a pot on for tea before she begins rummaging around to see what there is to be cooked. All three dogs eventually migrate in as well, to take positions sprawled at various locations around the kitchen floor. Soon Sable has pots on the stove and things being chopped or peeled or washed as the two of them drink tea, chatter about drawings and whatever else comes to mind, and just enjoy one another's company until the others return home...