I hadn't thought of Nick Fury as the priest but now he would totally have to be!
First I thought that he would be likes Steve´s dad....or maybe walk one of them to the altar, then excuse himself because there´s someting in his eye and then sit down next to Dum Dum and cry that his "baby" has grown up
or he simply sits there with a cigar, all confident and saying "That´s my boy up there" while feeling extremely proud^^