That's ironic because I think of all the main characters, Noah is the one it makes the most story-sense to kill off, not now but pretty soon. His role is just to be Claire's dad. When Claire grows up (or maybe I should say IF she grows up!), Noah has no further use in the story.
Given the dumb, season one Buffy way she's been acting and the slow manner in which "in-universe" time moves in this show, that's Chapter Fifty Eight then. (Where Hiro goes to the future and discovers the world is going to end and then travels back in time to stop it)
Personally, I think Hiro is the most useless character-wise. Poor Mo actually has a use in the story as the scientist who is trying to figure out a way out of the whole mess. Trouble is, he seems intent on making the mess even worse.
Hiro is a plot device. He is there to make the plot move - either by accident (season one), because of his romaticised obsession with the stories he heard as a child (season two) or because he was bored (season three).
Peter is Luke Skywalker. which makes him arguably the most important character. He's certainly more interesting/less annoying than the other Luke Skywalker in the story, Hiro, who the writers have no clue what to do with and therefore should just kill kill KILL HIM ALREADY!![]()
Hiro and Peter do have something in common - the writers keep crippling them to suit the story. Peter, however, is just useless now. Hiro, on the other hand, what would a ten-year-old with superpowers who loves comcs do if he found out the world was going to end ?
Claire is Peter's sidekick. I have no idea what that girl thinks she's doing, but I guess she has something to prove. At least she isn't stagnating but the more she progresses towards adulthood, the faster the clock is ticking for Noah...
Peter is Alfred, he's Jarvis, Gwen Stacy, Foggy Nelson, Ben Urich and so many other background characters now.
Actually, to use your analogy - he's gone from being Luke Skywalker to being C-3PO.