The Federated Suns carrier WarShip Enterprise was ostensibly stranded in the demilitarized system following a jump accident, closely watched by the SLDF destroyer Lancaster. On 31 December 2601, the Draconis Combine flagship Ryu arrived and claimed the same unlikely cause. As the two WarShips maneuvered towards each other in what was bound to turn into a military confrontation, several other vessels, referred to as merchants by an officer aboard the Prosperity space station, jumped out of the system or at least prepared to jump. The Mercurius was one of the first three ships to jump out.
The Mercurius only appears in the German-only novel En Passant. As a foreign-language product, this novel is not currently counted among the canonical BattleTech sources. It is an official BattleTech product though, and as such should be regarded as apocryphal.
- En Passant, p. 295