Isn't the fallen one both a herald and an Eternal like Thanos?
If so this would be SS facing Thanos mixed with a herald.
If not then fallen one can't lose if he has complete control over his molecular structure. The same way SS's blasts don't do anything to Thanos.
Thanos isn't an Eternal, he's a Titan. And labels mean very little if they aren't accompanied by power/feats. I think you may be right, but Fallen One still has nothing to his credit that comes within a sneeze of Surfer's best.
originally, titanians were separate but soon retconned to be titanian eternals. they weren't all present for the accident that granted the eternals cosmic power and immortality(thats probably what digi meant)
but they are extremely long lived anyway. thanos on the other hand is totally barred from death's realm so he can't really die.
Gender: Male Location: Following the Source of Light.
This is totally a matter of speculation, since Fallen One really hasn't had that many feats to his credit or discredit. I'd place him on par or above Classic Surfer and beneath the Current Surfer. Current Surfer wins. Classic, eh, it could go to the Fallen One.