Who did Ron turn into in Harry Potter and the Deathly Hallows part 1?

Ron Weasley did not turn into anyone in Harry Potter and the Deathly Hallows Part 1. He did, however, leave Harry and Hermione for a period of time during their search for Horcruxes. This was due to the stress and pressure of their mission, as well as the effect of the locket Horcrux.