They could run into one another in the leadup to the assassination when everything is getting nuts and people are running around in the streets? I don't have a set idea for outcomes but I imagine it's gonna be another clash where they get into it with one another. Since he's gotta get over there and kill Cyrus, maybe he can trap Dimitri or disable him somehow? Dimi is unlikely to end up in Highstorm post rail gun... or he could see him lurking around before everything kicks off and htey can get into it and yell at one another instead?