The St. Louis Blues and Chicago Blackhawks have as much history as many rivalries in today’s NHL. They do not have the cachet of Toronto and Detroit or Boston and Montreal. Nevertheless, they have been involved in some of the league’s most bitter encounters.
With that in mind, the thought of sending someone across the battle lines to join the opposing squad seems unthinkable. You almost never see rivals exchange players unless it is via free agency.
The closest in recent memory is Chris Osgood joining the Blues. He won Stanley Cups with Detroit, but he played for the New York Islanders in between, so it doesn’t really count.