Supergirl has a few ongoing mysteries right now (what's the deal with the guy from the pod?), but maybe the most personal one for both Kara and her sister Alex is the whereabouts of their father, Jeremiah Danvers. Thought to have died years ago protecting J'onn J'onzz, it was revealed that Jeremiah is alive, but being held prisoner by Project Cadmus. What exactly Cadmus has been doing with him all this time is unclear, but according to Andrew Kreisberg, they aren't in any rush to give out answers.
During Entertainment Weekly's Spoiler Room segment, Supergirl executive producer Andrew Kreisberg promised answers to fans' burning questions about Jeremiah will be answered in time. Right now the show has a more immediate problem to deal with in the form of Mon-El, the mysterious being from the space pod, so expect the Jeremiah plot to be dished out slowly.
The biggest takeaway from Andrew Kreisberg's comments is that Jeremiah isn't returning home in one piece. Cadmus has been doing who knows what to him for 12 years now, and there's little chance that that hasn't had a major effect on him. Cadmus must have big plans for Supergirl's adoptive father, which probably doesn't spell anything good for Kara or Alex.
As for what Cadmus could have done to Jeremiah, it's all speculation at this point- but fans with a watchful eye may already be picking up some of the clues. We learned last week that Cadmus has the technology to make their own super people, turning mercenary John Corben (and some other guy) into the kryptonite powered Metallo. Branda Strong's creepy Cadmus doctor also insinuated that something similar had been done to Jeremiah. We can probably assume Jeremiah now has superpowers -- more than likely with a healthy level of brainwashing -- and could be Cadmus' secret weapon against Kara. More importantly, this could all finally be leading to Cyborg Superman.
Comic book fans will know that Cyborg Superman's backstory is complicated, but basically whittles down to being a villainous cyborg with all the powers of Superman plus more. Cyborg Superman's human identity was Hank Henshaw, who in Supergirl was Jeremiah's partner before J'onn J'onzz stole his identity. It's possible that Cadmus will use a version of their Metallo tech to turn Jeremiah into their own controllable Superman. Jeremiah as a villainous Superman would also be a wink to fans who know that Jeremiah's actor Dean Cain actually played Superman on TV, and it would fall right in line with the stunt casting these CW shows love to do.
We'll see what's going on with Jeremiah in due time, and you can watch new episodes of Supergirl Mondays at 8 PM on the CW.