Jacobs' Emissary is a follower of Sir John Jacobs in Timeless Space[1].
The emissary was assigned to keep watch over Lady Noga. However, after she killed Shanklin and abandoned Jacobs' fleet, the emissary chose to defect and serve her rather than return and face Jacobs' wrath.
The emissary was originally a minion of Crushestro. He arrived in Timeless Space after being blasted out of the timestream by the Time Czar[2].