"Visit old friends" is an optional mission objective in Sequence 11 / Memory 01: To Suffer Without Dying
Walkthrough[edit]
There are 2 old friends for Edward to meet with. The first is found to the East of the second Alarm bell. Look at the cage nearby the building (close to the Animus Fragment). There you will find the first friend. Interact with them
The second found is found inside the prison. Make your way through the first few rooms. When you get to the first big room, look to the right of the entrance. You will hear rambling coming from that corner. There you will find another friend languishing in prison. Just hit the interact butt
