While on board the Finalizer, Poe is injected with some drugs, with hazy effects. He forgets in the rush between his escape and destroying Starkiller, but it soon is clear that the drugs are still in his system.

When he defies or challenges orders from anyone, he is punished with an immediate stab of blinding pain in his head. Resistance Medics can’t puzzle what’s wrong with him, until Finn puts two and two together and recognises the drug, having been on it before. It’s a First Order method to keep stormtroopers in line. The effects wear off after a few weeks, hence why his had gone enough to allow him to escape.

In the meantime Poe must struggle to not be his usual challenging self, and deal with the overwhelming pain when he inevitably fails.