* How long you've been with Firewall. For simplicity, I'm gonna require that all PCs are familiar with the organization. You can be a veteran or as green as you desire. Bonus points if you can tell me your relationship with the organization, but right now all I need is how long you've been with them.
I've yet to really consider how long Mark has been with Firewall, though he's been on at least three missions with them before the game begins. For the point of causing links with others, one mission had them do infiltration to gain intel from a specific server. Unfortunately this server was guarded and Mark was caught, but helped out by his team-mates. The second mission he was in of note involved a barroom brawl and when fists got thrown, the slightly naive Mark pulled out his gun and got some shots out... He was later brought back from backup when his morph got totalled. Final mission had him come across a potential X-risk black box on a transport. Without thinking he got his access jacks out and hacked it down then and there, even with the risk of nano-infection, it was the one thing he knew he could do.
* Where your PC is based and their IC explanation for traveling a lot.
Renrakubrug! IC, Mark is an Out'ster and just happens to spend his time in a pod on the brug. Noone really pays him any notice being a second class citizen with few connections, even with his curious nature. Lifestyle was as mentioned before, he has real basic stuff to keep his pod rolling along, though he mainly jumps ship and hangs in servers and simulspaces in his spare time.