The Keeper tunnels stretched further than the eye of could see and the Geth continued on knowing the long walk it had before it. Providing nothing stopped it, the Geth predicted it had at least two days of solid walking to do before it reached it destination. If it were an organic then the Geth could have taken transportation and reached his target within minutes. But he was a geth. It's appearance would cause horror and alarm, and his target would be aware of its presence. The Geth required secrecy. The shadow broker provided the targets itinerary and the Geth knew that Henry Lawson would be in the Citadel for a month. Time was not of the essence.
Either organics didn't know about or cared about the tunnels because the Geth never saw a living soul as it began the first leg of its journey. The Geth came to a full stop when he saw a Keeper crawl past. It took a moments thought but the Geth decided his previous statement was still accurate. The Geth had yet to see a living soul, it didn't consider the Keepers to have souls. To the Geth souls were important and the basis of the most important question to the Geth; do these units have a soul? It was the question that sparked the war between the Geth and their creators. The Keepers were nothing but puppets of the Old Machines.
"The old machines," The Geth, spitting the name out loud without realizing why. This Geth, before it had been upgraded and elevated to the platform it was now, worshipped the Old Machines as a god. In a former life this unit believed that by only having the Old Machines favour that the geth could be elevated to their desired state. But then the Shepard-Commander came and freed it and it's fellow units from the Old Machines religion. Then it was upgraded to the point where it could look back and realize its mistakes. The salvation of the geth didn't lie with the Old Machines. This Geths mission was to find out where it did lie, but not that didn't matter any more. All that mattered was revenge so the Geth continued walking. It had a long way to go.
Make love, not toast.