I think Christie was someone who Trump wanted to be VP, until Trump's plane had 'maintenance' issues and Trump was forced to stick around for a meeting with Pence which was Manafort's pick for VP.

Then Christie was put to overseeing the transfer team, which Trump shut down and yelled at Christie because they raised so much money for the transition that Trump wanted for himself. Christie of course tried to explain the money was needed for a proper transfer but we all know how that went. There's an article about that bit for those that may not have seen it.