Like the Duke of Buckingham in Shakespeare's Richard III, Mike Pence is a fundamentally hollow, immoral thug who was perfectly willing to help Trump win the White House and, once he was installed, perfectly willing to abet his every destructive, corrupt, totalitarian impulse -- all hinging on the promise of the rewards to come for his faithful, groveling service.

And then one day,  to insure his grip on power, Trump asked Pence to something that brought him up short.  Pence hemmed and hawed and stalled, and (I assume) behind closed doors gently reminded Trump of his faithful, groveling service up to that point and the rewards (we can all safely assume) he had been promised for that service.

But just as in the play, the minute Trump's Buckingham definitively refused to murder democracy in its bed in order to help a tyrant hang onto power, Trump immediately turned on him and began plotting his destruction.   

Duke of Buckingham: Is it even so? rewards he my true service
With such deep contempt made I him king for this?
O, let me think on Hastings, and be gone
To Brecknock, while my fearful head is on!

All of this evidently came as a complete surprise to Pence, who is a dull, generic Republican hack with "wit’s as thick as a Tewkesbury mustard" and who has obviously never read you-know-who.