Wasn't there a Robot Chicken that had Skeletor and Evil Lyn in bed, reading, and Skelly looks up from his paper and says, "I just realized your name is a play on 'Evelyn'..."
Keldor has portaled in from somewhere... another part of Eternia or another reality? Was the Sorceress doing the porting, or was she trying to stop it? Is this Keldor good or bad? Are he and Skelly friends or foes? All for the viewer to decide.