Upon seeing that opening vid, I actually thought all marines were convicts sentenced to death and put in the front line as their death penalty. But it seems to me that only Tychus has this deal with Mengsk. In that case, it is safe to assume that it was Mengsk who set Tychus to join Raynor's Raiders.
But in the ending scene, Tychus' orders seem to be actually to kill Kerrigan, not Raynor (I thought he was supposed to kill or bring Raynor to Mengsk). But for that to happen, was Mengsk expecting that Raynor would actually go and try to save Kerrigan? That it was just his convenience that Kerrigan was converted back?
Or was it a huge conspiracy of sorts where Mengsk told his son to get Raynor to help him become his father's successor (much more believable than Mengsk dealing with Raynor himself). I mean it was Valerian who researched and fixed the artifact right? So was Arcturus counting on that for Tychus to have a shot at Kerrigan?