Both my Rogue Trader dreads are meant to be ones that were on Caliban during the betrayal. During their transit in the warp, unlike many of the marines, the dreadnoughts of the fallen were forced to remain awake by the very processes meant to keep them alive. As a result many went mad, while other ripped apart their auditory and visual inputs to spare themselves from the warps unimaginable horrors. This one had to have the full containment capsule refitted to repair such damages.
While not the glorious emblems of the Imperium's strength they once were, they still house warriors of unimaginable prowess and experience. On occasion in the most dire of circumstances these dreadnoughts are called upon to provide their unrivaled might on the battlefield. In such cases a servitor accompanies the warrior, because without aid, the machine spirits of the dreadnought corrupted during their transit through the warp might take over and cause untold destruction on both sides.
Or at least that was what I was thinking.
-40k- Fallen Dark Angels - Astelan's Terran Loyalists : 1000 pts
-40k- Alpha Legion Chaos Marines : 1000 pts + Warhound Titan
-40k- Orks Speed-Freeks : 3000 pts
-Fantasy- Bretonnians : 500 pts
-Warmachine- Broadside Bart : 35 pts
-Infinity- Bakunin Nomads : 300 pts
2000 points in random models from LotR, Fantasy, and 40k