Then I experimented with Brioche knitting. Great technique! Loved the look! And it was really stretchy, which is a characteristic of Brioche. But for the life of me I couldn't find instructions on how to work it in the round. So in the end I settled for solid blue.
ETA: He thought they were fun, but the cast off was too tight to be able to slip them on without a struggle. On my next visit he sat next to me in the recliner completely absorbed in watching, while I undid the cast off and reworked it with a stretchy cast off. Success! He pulled them on himself, danced a jig and said excitedly, "I love these slippers Grandma. You're the bestest, most fun, nicest girl!"
Note: Later that evening he was charging around on the hard wood floors, slipped and landed hard. Crying, he ripped the slippers off, flung them and said, "I HATE these slippers!" I said, "Hey E., I have a thought. Maybe that's way they're called slippers." He was not amused.