It's just chemistry.
So Bryan Cranston's Walter White says to Aaron Paul's Jesse Pinkman on an early episode of Breaking Bad, and in an early scene from the following new trailer.
Taking fans back through highlights from what many believe is the best show on television, the promo prepares us for the end. Yes, Breaking Bad Season 5 - along with the series - will wrap up after the eight episodes that begin on August 11.
And, at this point, we all know the drama (along with dealing meth) is about a lot more than mere chemistry. Relive the past couple years and watch now: