Syd - "Mr. Trent! It's very important that you and I speak."
Trent - "And why is that?"
Syd - "Because we're the last two!"
Trent - "The last two what?"
Trent - "Wait, I know you! From the rescue ship! What happened out there?"
Syd - "They were looking for something. I'm a thief, Mr. Trent. I came to Freeport 7 to deliver something that a certain party wanted very badly. Apparently they weren't alone...
Trent - "You're telling me this is all because of you?"
"It's not really about me, Mr. Trent... it's about this." *Syd reveals and egg-shaped glowing purple Artifact* "This is what they're after. And now they're after us... We need to get as far away from here as possible!" *Syd's eyes widen, he whirls to run away, and is shot in the back, killing him. The Artifact rolls a few inches from his open hand.*
Syd was an unnamed character in Freelancer (his name is revealed in rumors and news, but is not spoken in dialogue). He survived the destruction of Freeport 7 with Trent, Lonnigan, Brandon Rowlett, and others. At the beginning of Mission 1, he can be seen briefly with the other survivors leaving the craft; after Trent is met by Lonnigan for the first time before Mission 2, Syd can be seen smoking on top of a balcony overlooking the landing pad, ominously watching events unfold.
Later, when the plot thickens, he is shot dead by a LSF operative in cold blood while he was showing Trent the Dom'Kavash Artifact on the landing pad at Planet Manhattan. After Juni stops and then kills the rogue operative in self-defense, Trent takes the Artifact and they begin the escape from Liberty.
It is possible that this character model was originally planned for someone possessed by a Nomad, as beta footage screens show him wielding a fist of purple light.
Syd, by virtue of his very survival in Liberty and retention of the Artifact despite obvious shadowy goings on in Manhattan, is very likely an experienced operator of one sort or another. Though he claims to be a mere thief, Syd seems confident that his buyer wouldn't double-cross him (or at least wouldn't dare blow up Freeport 7), as he seems to think someone else wanted the Artifact (it us not revealed if Syd saw the Nomad ships before the station was blown up).
In any case, if his original buyer intended to betray him, the buyer probably would have simply quietly disposed of him, rather than blowing up the whole station to get him. This would indicate that the Nomads or their agents were not the original buyers, and did not know who had the artifact, only that the exchange would take place on Freeport 7. Instead, either The Order or another extremely wealthy party was the prospective buyer. It's even possible that Trent's million credit "Boron" shipment was intended to be nothing more than a Trojan Horse to hide the artifact in, and Trent a patsy courier. This would go a long way to explain the supposed million credit payoff for a simple haul of Boron.
Due to the way he's dressed, he's presumably a Zoner, as they use similar clothes.
"I just had a conversation an hour or so ago with a guy named Syd. He just told me that he's in the possession of an alien artifact and that it is the reason for all the catastrophes lately. You'd think he's just a nut case, but you know, he seemed eerily serious and convinced." - Ian McDavid, Lane Hackers, Mactan Base (shortly after Syd's death)