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.
Branda Strong’s creepy Cadmus doctor also insinuated that something similar had been done to Jeremiah.
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.