Éothain was a rider under Éomer's command. He was present when the Rohirrim overtook the band of orcs that had captured Merry and Pippin. Éothain wasn't as trusting as Éomer because he laughed about hobbits even existing, and was reluctant to give horses to Aragorn, Legolas and Gimli when they encountered them on the plains of Rohan.
Encyclopedia entry originally written by rider_of_rohan32190