Sizemore seems to have been Parson's first friend in Erfworld. The two respected each other right away. Sizemore had never received any respect from a Warlord before, so he naturally treated Parson the way he would treat one of his fellow Casters in the Magic Kingdom. Sizemore's attitude toward Parson suffered when Sizemore was ordered to kill enemy units, but Sizemore seems to have forgiven Parson.
Sizemore enjoys learning new ideas and performing new tasks, as long as they don't directly involve croaking people. He therefore appreciates Parson's capacity for suggesting ideas and activities which are new to Erfworld. He knows that associating with Parson is likely to increase the rate at which he levels. But he is also apprehensive about Parson's capacity for mass slaughter, and dislikes the effect Parson's innovations are having on his relations with the casters in the Magic Kingdom. While Janis helped him come to terms with the death toll produced by "uncroaking" the volcano, he knows he may find it harder to forgive what Parson makes him do in future battles. By the time the Siege of Spacerock is over, Sizemore shows a great deal of antipathy, and Parson acknowledges that Sizemore probably hates him now.