A doppelgänger is a double, a second self that follows you around, and this short poem sketches one in a few bold strokes. The opening lines are the strangest: "who goes with me / whoever I am." The speaker doesn't seem sure who the "I" is, which makes the double feel less like a copy and more like a companion who may know the speaker better than the speaker does.
Then the poem becomes a portrait. This figure was "born with a beard / like a red bush / thick as gossip," a funny, vivid comparison that makes the beard wild, overgrown, and a little noisy. The smile is "like fire on Christmas," which suggests warmth and cheer, though fire can also be unpredictable. The mood is playful and affectionate, with a hint of unease underneath. The speaker seems amused by this other self, even fond of it, but still can't quite pin down where one person ends and the other begins.