A hypercorp supervising engineer from Earth orbit who knows the ins and outs of the corp system.
The remains of hypercorp he worked for on Earth have finally cleared the legal system and gone to auction. He ends up under the contract of his current employer's direct competition due to commitments made before the Fall. A legal battle over who "owns" his employment could ensue, or one group could claim all his engineering projects for the post-Fall company as intellectual property of the corp that owns his old contract. The hypercorp that newly acquired the contract could approach clandestinely as well, blackmailing the character into corporate espionage against his nominal employer.
An autonamous psychologist "kidnapped" by uplifts during the Fall and currently sleeved into a neo-homid gorilla. He wears a top hat.
Ummm...not a human at all, I assume? The kidnapping story is to obscure her identification as a self-hating uplift. Her love of psychology comes from a deep desire to be fully transhuman rather than an uplifted primate. She's, at best, a mercurial apologist, at worst an uplift Uncle Tom. An anti-uplift hate group on Mars could find out and destroy her hopes for cultural assimilation, or a Mercurial terrorist organization could target her as a collaborator
A Venusian orbital smuggler.
Shit. Not much there, is there? Maybe the smuggler is actually being paid under the table by Morningstar. His job is to arrange the hijack of a massive iceteroid being re-routed into Martian orbit from the belt. Stealing it would go a long way to terraforming the Venusian upper atmosphere, with the added bonus of dealing the PC a sizable credit and PR blow. All he has to do is get aboard the rock and reprogram all the thrusters with new telemetry. However, his involvement has to be completely clandestine; his capture could spark a war. Maybe he doesn't even know he's working for the government, either due to proxy hires or edited memories.
A Lunar Night Cartel morph lean enforcer.
Night Cartel has a lot of competition on Mars. Les Ghoules, Nine Lives, ID crew, and the Luna Organization all have inroads to the major Martian settlements. Maybe the enforcer has to juggle Firewall work inbetween assassinations on big players in other organizations. Maybe there's an underworld war taking place in the background. Maybe she's charged not with killing the morphs of big players, but demoralizing the competition by grabbing the stacks of their loved ones. Why does the character do these horrible things? Is he/she loyal Costa Nostra or do they have something to hold over the character?
A post-human synth-rights activist who loves resleeving.
Hmmm...Maybe invent a new addiction and give the player extra CP for it. They feel the need to resleeve. Bodies get boring after awhile, like people who constantly trade in their cars for the newest model. Maybe have them feel the itch for newer, more exotic morphs. Perhaps the need to experiment with sleeves starts to harm the player's activism. It's tough to give a stump speech on synth-rights sleeved in a modded Fury morph. It also will provide a huge financial drain on the player.
A brinker outback Martian who supports Mars becoming independent.
Easy. Organize terrorist attacks and make scavenging runs into the White Zone. Have the Barsoomians learn about a players Firewall involvement and demand the character use the conspiracy to further Barsoomian goals. Split the loyalty of the character between Martian politics and dealing with X-threats.
And a hypercorp infomorph genehacker who dreams of a bio-terraformed Mars but has to do "favors" for the terraforming corps to keep her underground lab from being the center of an unfortunate geological event.
Is she indentured? Is she an informorph or infoLIFE? Hmmm. If she's just an indentured person, have her "sleeved" into her threatened lab. She can only do missions in puppet socks or as a fork. Threats on the lab or threats are threats on her existence. Maybe the hypercorp is demanding some seriously questionable gene work, like engineering bioweapons or mapping TITAN genetic materials. If she is infolife, use real world naivete to have her engineer some truly distasteful morph that becomes popular with a particularly disliked faction. For instance, a really cheap Shaper variant that becomes a favorite for suicide bombers or something.
I'd be sure to give your characters enough time to play so that they can secure their own backstories as they get inspired. Everybody is reticent about themselves when they meet new people anyway. The characters can warm up as the players do.
Of course, if they get to game 8 or something without telling you anything, just make their consciousness shareware :-)