Family was a big theme for Season 1 of Supergirl as Kara had to deal with the ongoing sorrow of losing her family on Krypton as well as the more recent grief of the death of her adoptive father Jeremiah. Martian Manhunter discovered, via telepathy, that Jeremiah might not actually be quite as dead as the Danvers sisters suspected. A vision of Project Cadmus revealed a Jeremiah who was alive and looking pretty ready for a rescue by his daughters. According to Supergirl executive producer Andrew Kreisberg, however, Manhunter's vision doesn't necessarily mean that the Jeremiah at Cadmus will be the same man he once was.
When asked about what's to come next on Supergirl, Andrew Kreisberg had this to say about Jeremiah Danvers in Season 2:
For those of us who had taken Martian Manhunter's vision of the living Jeremiah at face value, Andrew Kreisberg's comments to EW just made hiatus a little bit tougher. Kara and Alex didn't even seem to question if the Jeremiah they're hoping to rescue might be seriously altered from the Jeremiah they knew and loved, so it was easy to assume that the rescue operation would end in a Supergirl happy ending. If Jeremiah has changed for the worse - whether due to physical changes via experimentation or prolonged emotional trauma - there may be no happily-ever-afters for the Danvers family.
Project Cadmus was introduced in Season 1 as the reason why Superman won't work with the U.S. government in the Supergirl universe. It's a program that often turns to dissecting and experimenting on aliens in order to find out as much information as possible by any means necessary. Martian Manhunter was in for a rough ride at Cadmus when the D.E.O. discovered that Hank Henshaw was actually an alien named J'onn J'onzz, and the very human Alex was being shipped to Cadmus along with him as punishment for her role in protecting Manhunter's secret. Supergirl never got too specific about what Cadmus could have planned for Alex. It didn't sound good, though. Luckily, Kara was able to rescue her sister and their mentor before they reached their dastardly destination.
If Supergirl is going the Superboy route in Season 2, we may soon learn that humans are brought to Cadmus for cloning purposes. Alex escaped experimentation, but Jeremiah has presumably been a prisoner at Cadmus for a while. There could've been plenty of time for the sinister scientists to harvest his DNA to create clones. Surely having his DNA harvested to create alien/human hybrids would be enough to change any man. Who knows? Maybe the Jeremiah that Martian Manhunter saw in his vision was a clone himself. A cloning process could definitely result in a Jeremiah that his daughters as well as the audience should question in Season 2. All in all, science gone wrong is a classic way to turn good guys bad in comics, and that could be the case for Supergirl.
Only time will tell what Supergirl has in store next for Jeremiah Danvers and his daughters. The show will be moving from CBS to The CW, so it'll likely look a bit different when it returns to the airwaves this fall. Check out our summer TV premiere schedule to see what you can watch in the meantime.