To Rhianus in his epic Aristomenes is the hero and he is to him a great men as is the Achilles of the Iliad to Homer (IV 6,3). The Aristodemus of Myron is a bit earlier than the Aristomenes of Rhianus. Myrons history of the Messenian war is in prosa, Rhianus has made an epic.
In Rhianus's epic, Aristomenes is the main character and is regarded as a great individual, much like Achilles in Homer's Iliad (IV 6,3). The earlier work on Aristodemus by Myron occurred before Rhianus' account of the Messenian war, which was written in straightforward prose, whereas Rhianus created an epic poem about Aristodemus.