Politicians demand loyalty all the time. It's one of their most prized assets. As a neophyte politician, it's not surprising that Trump would ask for it from someone he was soon to appoint to a job. 

It's inappropriate for an elected official to ask for loyalty from a civil servant, of course. Likewise for Trump to ask Comey to "let it go" in reference to the Flynn investigation. But was there criminal intent involved? Hardly. 

Notably, Comey didn't attempt to explain the situation to Trump, to enlighten him about the separation of the executive from law enforcement. It was almost as if Comey was hoping Trump would say something truly stupid. And if he had, Comey would still be the Director of the FBI today.