These are the decisions made in Mass Effect which are used for this story.

Relevant decisions of Mass Effect trilogy

Shepard's profile:

-Male.

-Spacer.

-War hero.

General:

-Shepard chooses all paragon decisions.

-Shepard has a romance with Liara along the trilogy, and he remains faithful to her. He has romantic relationships with nobody else.

Mass Effect 1:

-Once you can leave the Citadel, the first mission is "Find Liara T'Soni".

-All team members recruited.

-At Virmire, Wrex survives. Kaidan dies.

Mass Effect 2:

-All team members recruited, including Zaeed and Kasumi.

-Shepard doesn't trust Cerberus.

-All loyalty missions successfully completed.

-Shepard accepts reinstatement as a Spectre.

-Samara kills Morinth.

-Tali wasn't exiled.

-Grunt joins clan Urdnot.

-Maelon's research data about genophage saved.

-DLC "Lair of the Shadow Broker" completed.

-Normandy fully upgraded.

-All team members are loyal.

-The last mission before passing through the Omega 4 relay is "Legion: A house divided".

-Everyone survives the Suicide Mission, both Shepard's team and Normandy's crew. Collector base is destroyed.

Mass Effect 3:

-"Extended Cut" installed.

-All secondary missions successfully completed (Tuchanka, Rannoch…)

-DLC "From Ashes" completed.

-Liara meets Aethyta.

-Liara shows Shepard her time capsule.

-Doctor Chakwas and engineers Ken and Gabby return to the Normandy.

-Shepard encourages Joker in his relationship with EDI.

-Genophage cured.

-Shepard gives Miranda access to Alliance resources to find her sister.

-Ashley joins the team.

-All missions of Mass Effect 2 team members are successfully completed. Jack, Kasumi, Grunt, Zaeed, Samara and Jacob survive.

-Peace between quarians and geth achieved.

-DLC "Leviathan" completed.

-At Thessia, Javik goes with Shepard and Liara. Back in the Normandy, Shepard calms Liara in the argument she had with Javik.

-Miranda survives at Horizon (her sister too) and she kills her father.

-Shepard convinces Javik to use his prothean echo shard.

-DLC "Citadel" completed. Party completed.

-Shepard helps EDI understand organics.

-Minimum effective military strength: 3100.

-On Earth, Liara is part of Shepard's squad in the final push towards the Conduit.

-When speaking with the Catalyst about the possibility of controlling the reapers, the answer "I'm not losing anything" is chosen.

-Destroy ending is chosen. Shepard's team survivors: all Normandy's crew, Ashley, Garrus, James, Javik, Liara, Tali, Jack, Kasumi, Grunt, Zaeed, Samara, Jacob, Miranda and Wrex.