- Three cover kills
- Keep up with Bellec
Kill the Guards and Sabotage the Bell
Your first objective is also the most logical place to complete the first challenge, but it should be noted that challenges are optional, so you could jump into the middle of the courtyard and slay your foes with some expert swordsmanship.
We'll assume you want the cover kills, and the first order of business is helping you understand what they are. A cover kill can be performed at any time when you are using the cover mechanic and locked onto an object. Imagine yourself hitting the cover button at the corner of a wall, causing Arno to stick to it as he hides from his adversaries. If one of your enemies were to approach Arno's position, you could press the attack button to ambush them. That's a cover kill.
From the position that Bellec and yourself look over the courtyard in the opening cut scene, imagine the four walls of the courtyard as the bottom, top, left and right. For our purposes, you are on the bottom, and you want to use your parkour skills to get to the right wall by traveling in a counterclockwise direction. Don't head to the top wall. Just drop down into cover behind where the guards are moving about. It's here that you can start to setup your cover kills, focusing on one guard at a time.
When all three guards are dead, approach the bell in the middle of the courtyard and sabotage it, kicking off a mid-memory cut scene.
Loot the Evidence
This is an easy one. Approach the guy that Bellec assassinated in the cut scene and choose the option to loot his body.
Escape the Conciergerie
This is where you can complete your second challenge of the memory, and it's a simple as keeping up with Bellec. Most of this is done using the free run option, but there is the occasional place where you may need to drop to the ground level or make a leap of faith. The point is, chase after him and try your best to keep up. If you want to, you can even kill some folks along the way.
Go to Cafe Theatre
It's a new objective, but you have to do the same thing that you did before, and that's to follow Bellec through the streets and over the rooftops of Paris.
Go to the Assassin Headquarters
Follow Bellec for about 10 seconds to complete this.
Go to the Council Chamber
Assassin's Creed Unity really knows how to give you a cool down period to end a memory. Just like the last few, this one is nothing more than following Bellec. Just walk and talk, paying attention to what your friend has to say. When you finally reach your destination you'll trigger the memory ending cut scene.