Letters are matter of speculation. Seems apparent that the conversation about Rule 9 indicates something was up their sleeves. Could have been public scandal (perhaps Stormy), maybe 187, but doubtful at that point.
Pence, possibly selected to calm the DS, at least if they do 187 Trump, they got their new president ready and waiting.
Pence is a grey hat. Q/NSA/Trump has something over him.