Ivan stayed where he was, struggling a bit to stay afloat. He was small and very skinny, so he wasn't naturally all that buoyant. He watched Raven floating downstream, and not wanting to be separated from the only companion he had he followed, letting the water pull him downstream. He was still a bit cross with the young man, but he realized in retrospect that doing this was probably the only thing they had left to try. Staying up in the tree and waiting for death wasn't any smarter.