Geldhoff is a Latverian teenager who was exposed to the Terrigen Mists, transforming his appearance and giving him newfound powers. In the comics he initially runs into the X-Men, who he is scared of, and that role could be fulfilled by other Inhumans in the show (especially since they're shaping up to be the MCU's answer to mutants, given Fox have the rights to them). He's then taken into the custody of A.I.M. (Advanced Idea Mechanics (they really just wanted to use that acronym)) a terrorist organisation, and again their role on the show could be replaced, most plausibly by Grant Ward and whatever remains of Hydra. He can release purple waves of plasma from his body, which should be doable on TV, while his appearance wouldn't be too much of a problem, given the work they did with Raina last year.