queencalpernia and I were talking, and since we’re both incredibly pissed by the trespasser DLC, I brainstormed the DLC we could've had instead. A Return to the Marches, mainly it covers:
1) Exploring the Inquisitor’s background; we meet the Inquisitor’s family, learn more about their origin, and meet some of their friends and learn about their lives before they were the Inquisitor. Trevelyan mages can inform Josephine of their Circle’s fate; joined the loyalists, the rebels, declared neutrality, or was annulled, and can then give their opinion/voice their feelings on it.
-You can discuss your upbringing with your followers/love interest, and certain companions have unique dialogue depending on your origin (Iron Bull with Adaar, Solas with Lavellan, Varric with Cadash, Cassandra with Trevelyan, mage or no).
2) The main storyline is tracking down Anders/Justice (as the devs mentioned while Anders might be dead, Justice is another matter) and eventually you do, and you can bring him in for judgement. You can execute him, make him Tranquil, turn him over to the Chantry, or let him go (this will severely hurt approval with most followers). Trevelyan mages get special dialogue here.
3) You also go to Starkhaven, and meet Sebastian, and you decide wether to keep him on the throne, or put someone else on it. The decision Hawke made with Anders/wether you completed his war table mission matters here.
It opens with Josephine asking you about your background, and then an origin-exclusive person comes to visit. Non-mage Trevelyans get a sibling, mage Trevelyans get another mage from their Circle, Adaar gets someone from their mercenary company, Lavellan gets someone from their clan, and Cadash gets another Carta member. They end up coming along for the ride when Leliana informs you she has the location of Anders, and Cullen suggests turning your attention to the Free Marches and assist with relief efforts.
The mutually exclusive will be a NPC, but will follow you, and have some amusing party banter with your companions, especially if one is your LI, and will tell stories about the Inquisitor, who can interject and add their own pieces.
However, that exclusive follower can turn against you if they don't like what you've done; for the non-mage Trevelyan follower, using your position for personal gain for example, or a mage!trevelyan, turning a mage Tranquil/allying with the templars/conscripting the mages, for Lavellan, doing/saying anything pro-Chantry/accepting beind the Herald, to start with. For Adaar, again, abusing your power/being too nice with nobles/ignoring the racism Qunari face, for Cadash, being tyrannical, forgetting your origin as a Carta member; if you hit too many strikes with the follower, they'll attack you and you'll have to kill them.
This prompts an emotional scene with your LI, who will try to comfort you, and then you can reveal if you and the follower were romantically involved.
It's basically a Citadel-style DLC. Plenty of silly stuff with your followers, and new scenes with you and your LI.
When you go to Kirkwall, you actually see and speak to the companions from DA2 (if they survived) and see the effects of Hawke’s decisions. Varric gets a lot of special dialogue.
There's a scene with Iron Bull that's exactly the scene with Grunt and the C-Sec officer in the Citadel DLC.
There's another stronghold you can get from the Trevelyan family in Ostwick; if you're a Trevelyan, they're your parents. Trevelyans get special dialogue here, and your stated relationship with your parents in that conversation with Josephine in the beginning of the game affects the dialogue.
You meet the Valo-Kas mercenaries in Starkhaven, and if you're an Adaar, you get special dialogue, and you can recruit them as agents for the Inquisition, and count as a perk under Forces.
You meet members of the Carta in Kirkwall, and if you're a Cadash, you get special dialogue, and you can recruit them as agents and they count under Secrets.
In Tantervale, you meet Clan Lavellan (if they survived), and if you play as a Lavellan, you get special dialogue, especially if you're the Keeper’s First, and you can recruit them as agents under Connections.
You can introduce your LI to your family, depending on who it is will get some amusing responses.
This DLC allows you to customize the Inquisitor’s room, with Chantry/Circle/Dalish/Dwarven/Qunari decor; can also add pots for plants, images of your family, weapons/books/bottles, etc, and will also allow you to completely repair Skyhold.
The Inquisitor also gets a pet; an owl, a cat, or a dog.