In this video guide I will explain how to view Louis's memory echo. Now first things is you need to know where to access them. Talk to the girl that you woke up with over by the juke box and bed. Next is that these memories will be scattered around the maps to collect. They glow red on the ground and differ from items. If you uncover an entire map and see some small x's on there, make sure to go and grab them. They might be some memories so get them all to be safe.
To get Louis's memory you will need Hunter Vestige 1 and 2
. Upon repairing the second memory the achievement will pop. Just make sure to explore all areas you come across. You should get this achievement not too long after beating Oliver.
Another thing I am unsure of is if the memories are a set place in the game for everyone or just random. So let me know in the comments which it is. Thanks.