Me and @thealmightym got off on a HUUUUGE tangent this morning, upon the suggestion that the Inquisitor + love interest might show up in DA4 based on how the romance loads into game (assuming the Dragon Age Keep continues to function as well as it has so far:
I can totally imagine a storyline where, if you import Solas-romance inquisitor, as the new DA4 hero, you have inquisitor tag along on occasion. If you fuck up at the missions with them, inquisitor joins Solas in trying to wreck the world. If you complete all the missions with them, they take your side in the end fight with solas.
You can join them on their farm for a side mission or two. One of the side-plots is Inquisitor helping hide Cullen's younger sibling from the newly formed circle/templar/whatever as young sib is starting to have little magic bursts. It's equally fretful and adorable.
Inky and Bull have formed a new Bull's Chargers. If Inky wa Qunari, there's some of his/her old Tal Vashoth band joined up now as well. They show up as a random helpful encounter aiding you in world events. If you run into them enough times, they come to you asking for help on a diplomatic mission, Halamshiral style side event. It ends in the whole crew being chased out of the party for wrecking EVERYTHING and if you play your cards with, a menageāaātois with your old Inquisitor+bull plus new MC.
This oneās easy. Inquisitor and Sera are married GAY AF ladies who show up as random encounter in urban settings. Only instead of helping YOU, they drop you arrows with notes on them of missions that need your specific flavor of diplomatic aid. Missions like: having you seduce a noble lady/gent while they steal said nobleās unearned goods. Stabbing a few really shitty nobles in the junk in a painful but non-lethal way. Immediately lose missions if guards or innocents harmed in process. Poisoning the food at the banquet of a robber-baron so everyone in the party gets diarrea BAD. Oh, and their skin turns purple for a week. And bees follow them.
You meet them at missions in Weisshapt if Blackwall was told to join. Inq has joined them there indefinitely, and the two of them are the only two allows to Orlais & Fereldan as diplomats after that whole Wardens-turning-kinda-evil SHITE. They send you on a variety of one-off 'kill this monster' type missions, culminating in another encounter with the Architect, who can either help you by giving you something to defeat Solas, or you can fight, or they paralyse you and walk away without giving you ANYTHING depending on your game choices.
If inquisitor pardoned Blackwall, you run across the two of them in a cabin in the woods somewhere, trying their best to keep under the radar as they raise a couple of boys as out-of-the-limelight as possible.
Her ending goes one of three separate ways. Either she's got the bandit fleet under her wing, or her family has kinda lost status by the end. Or she's kinda bloodthirsty and killed some peeps.
I'm seeing their ending influenced by Leliana. If Leliana NOT Divine: Leliana is stealthily traveling alongside Inky & Josie to continue acting as a spy/ pulling strings of various nobility. While the peasants donāt suspect anything, most of the nobles are bloody terrified anytime Inky+Josie (and the unseen Leliana) roll into town because it means a few shitty nobles are gonna just be snatched away without a word. Inky+Josie show up as a set of espionage missions on war-tabley thing, and you can also interact with the trio at parties/ open-world spots where nobles show up, etc. Inky will very dramatically foil an assassination attempt on MC in DA4, starting a mission that culminates in an odd scavenger-hunt/goose chase of missions, culminating in Leliana identifying a spy within (DA4 organization here) who is trying to corrupt MC with magic. This traitor is not found in any other storyline, but is present in all other storylines (finger waggling here).
Josie+Inky IF Leliana IS Divine: series of wartable missions where Josie is convincing (DA4 group) to aid the Divine on various missions. Culminates in Inky foiling assassination attempt on YOU, and then enlisting your help to foil an assassination attempt on the Divine. Meanwhile, Josephine has been kidnapped, the Divine attack a diversion.
You go on a goose-chase of missions to figure out where they're keeping her, and when you finally get there, Josephine has things well in hand, and has a group of thugs tied up, and is regaling them with stories so entertaining that they're fallen over laughing despite being tied up. She looks over at Inky, who looks back at her lovingly, and says, "What took you both so long?"
Inky + Cassandra have put away (most of) their adventuring, and have opened a bookshop.
Cassandra very convincingly makes a good bookshop owner. She recommends a different book each time you come in, based on what events you've finished/ things you've decided in game. "I see you came back from Hamalshiral. Can I recommend 'My Lady's Coattails'? It's a VERY saucy period piece with a side of court intrigue."
At a later date, you find her in the midst of dealing with several unconscious people in the shop, half her battle gear on. Turns out she's been doing some do-goodery on the side, and doesn't want Inky to know. She enlists you to help deal with a local thug who has been threatening the shop and people in town.
You go and deal with the thug, and turns out it's WAY more than a local thug. It's a REGIONAL thug, and it turns into a whole long mission, halfway through, you run into Inky who was sent along by someone else in (DA4 group) because people heard DA4-MC and Cass got in over their heard. There's a whole scene of Cass being mortified that Inky found out, Inky being like, "Don't be. I'm missing and ARM and you're a bad-ass, why would I keep my wife from helping people?" And they kiss and it's equal parts adorable and awkward in front of you. They cough and you proceed to PUMMEL the lead bandit-dude.
When you return to the shop, you still get nod-to-game book recs for the rest of the game.
If you die more than a certain number of times on any one mission, Cass will sarcastically recommend, "Gennevive's Sword Primer". Inky interupts to ask why the non-fiction book. Cass sneeringly jokes, "Because our MC needs to work on fundaments."
I feel like his is the hardest, because he has such a FIXED position in the DAI wrap-up. And given that everyone assumes the new game will center on Tevinter, he'll probably be a central or pivotal role the story nods to or revolves around.... Hell, maybe it's just this...
MC has several encounters with the Magisterium. Dorian is actually one of the most consistent council members. Despite his distaste for the High magisters of Tevinter, once he was shoved into the role of leadership, he used red tape like a weapon, pissing off a LOT of other politicians who were perfectly happy with things being as easy for them to rule as possible. If Dorian was romanced by DAI Inky, there are several events where you can see him being uncharacteristically called away from a meeting, and if you follow, can see an event where he meets with his foreign lover for a small chat and a furtive kiss.
At this point an event occurs where another council member offers to aid (DA4group) financially or politically if they can get dirt on Dorian. You're lead down a series of espionage missions where you copy the communication crystal, and can either aid Dorian by re-tuning it to crush the other council member, netting you a series of side-quests lead by DAI Inky to disrupt more blood mages outside Tevinter, or you can hand over the communication crystal to Dorian's rival, and have an instant massive boost in faction points towards Tevinter Imperium/ who-the-fuck ever, cause let's face it it's the edgelord choice you gotta put in the game for people who insist on wanting to play shitty-evil person, ābecause reasonsā.