If your PCs switched places, who would they romance?

If my Warden Surana was in DA2, she'd have romanced Isabella, I think, and if she'd been in DA:I, probably Iron Bull, because she's kind of kinky and has no problem with people thinking dubious things about her.

My F!Hawke in DA:O, definitely would have romanced Zevran, and in DA:I would have romanced Blackwall, because she likes broken men but not crazy broken.

In DA:O, if my F!Lavellan rogue had to choose, she would probably have stayed single in both games, though in DA2 she might have gone with Fenris if he got over himself more quickly. My F!Lavellan mage would have gone with Alistair in DA:O, and then Anders in DA2, weirdly enough since now that I think about it she's not really all that concerned about being with another elf, like my rogue, it's just that she hit it off well with Solas.

I have to skip Hawke, but I have a lot of others...

Assuming they had never been the Warden/HoF...
If my Surana was in DAI, Cullen, hands down (after they cleared the air a bit, anyway.)
If my Tabris was in DAI, she'd be with Leliana, regardless of official romances.
If my Brosca was in DAI, definitely Harding. She'd like Harding's cheekiness
If my Mahariel (f) was in DAI, hmm, possibly Sera. They'd have had a few rows about Sera's attitude toward elves, though, so not sure how well it would have gone.
If my Mahariel (m) was in DAI, (after looking pensively at Morrigan) Cassandra. He likes them abrasive with a lot hiding under that.
If my Aeducan was in DAI, Josephine. She's my only one who wouldn't be bothered by the fluttering, and she'd get Josie.
If my Cousland was in DAI, she'd have made a try for Cassandra, then Cullen. Maybe. I'm really not sure about her...

If my Volya Lavellan was Warden in DAO instead of in DAI, Zevran absolutely. He's laid back, funny, and not bothered by magic.
Derzka Lavellan and Alistair (though it would start shaky, she doesn't trust humans)
Zhenya Cadash and Zevran - good looking, flirtatious, uninhibited, and she'd understand how much he was hiding under the humor.
Rezka Cadash and Zevran - she likes dangerous, self-confident men.
Vetra Cadash and Leliana - she'd be fascinated by both her faith and her background as a bard.
Strazh Adaar and Morrigan - she'd growl at him and he'd just grin down at her and not believe a word of it (not that he doesn't think she's incredibly dangerous, just not prone to harming people without reason.
Grandma Taina Cadash would have made a play for Sten, then probably have coaxed Bodahn into her tent... Because the canon romances are children

From what I've heard about sarcastic Hawke, I think she'd be cute with Alistair. Two wiseasses cracking jokes all the way to the abyss.
I'd pair up the Warden from DAO with Blackwall just for laughs. Except for Amell/Surana. They deserve to have a chance with Cullen!
If noncanon pairings are allowed, Lavellan would probably crush hard on Duncan, and Adaar would try to hit on Sten. Cadash with Oghren because Oghren can do sooo much better than abusive Branka.

DAO:

Hawke: He wouldn't have romanced any of the companions, but would marry Anora and execute Alistair as potential threat to the 'peace.' He would have let Loghain die an honorable death fighting against the archdemon. He has no patience for assassins so Zevran would be dead and he would've supported annulment of Ferelden's Circle. He is allergic to dogs and would think that there are more important matters than finding flowers to cure one. Sten would also be left to rot, Hawke doesn't care about qunari heretics or criminals. After the war he would send his spies to track Morrigan down; she's a dangerous apostate as well as a traitor.

Lavellan: She wouldn't romance anyone. Alistair's schoolboy crush is cute, but she would only care about him as a friend. Same with Zevran. Lavellan wouldn't recruit Leliana. I like Leliana in DAI, but in DAO she's just a Chantry cheerleader. Sten and Dog would be recruited, mages supported and Alistair would become King of Ferelden. Morrigan and Lavellan would probably rarely see eye to eye on matters... Morrigan has little regard for life and enjoys cruelty. Loghain would do the dark ritual with Morrigan and later die killing the archdemon.

DA2:

Surana: Anders, definitely! They were already flirting in DAA. Surana would support any actions taken to support mage freedom and would enjoy the chaos of Kirkwall. He would sleep with Isabela and Fenris (nothing serious). He would give Isabela to Arishok (nothing personal, just business) and happily help mages kill templars in Act 3. Justice and Surana didn't have much respect for one another (he sided with the baroness) and that would add an interesting layer to his relationship with Anders. Surana would greatly approve of Anders blowing up the Chantry and giving the first push for mage-templar rebellion. He would be proud of him, like a mentor is proud of their apprentice.

Lavellan: She wouldn't romance anyone. I love to imagine her and Merrill becoming best friends. She would help her repair the Eluvian and Merrill could teach her what she knows about blood magic. I think Lavellan would pity Fenris, because it's obvious he has suffered a lot, but also not quite know how to act around him. Lavellan loves magic and Fenris' hate of it would be both confusing and sad, because she would understand why he feels that way even if she would not agree with it. I think she would try to little by little make him see that there is nothing evil about magic (it only exists in the hearts of men) and perhaps once he trusted her ask if she could study his lyrium markings (and maybe try to take away some of the pain they cause him and try to help him regain his memories). She would support the mage freedom and Anders. She would be very curious about his connection with Justice.

DAI:

Surana: My first playthrough of DAI was with Inquisitor who was very much like my Warden and I romanced Dorian.  They were perfect for each other. Truthfully, I don't see Surana committing to one relationship with anyone or starting a family (he only stayed with Morrigan and Kieran because of the Old God soul thing and now that it's gone...) He just likes to have fun. He would drink from the Well of Sorrows because how could he resist the temptation? Later he would find a way to undo whatever hold Flemeth has over him just like he undid the Calling. His personal freedom is more valuable to him than anything else. Surana's old friend Leliana would become the Divine. He would be proud to see how much she learned from him. Inquisition would exist first and foremost to serve Surana's personal gains. Defeating Corypheus would just be the mandatory thing he must do to remain in power. He would let people worship him as Andraste's Herald and use their belief to stay in power long after Corypheus is gone (no Exalted Council could ever make him disband the Inquisition or serve the Chantry).

Hawke: Unlike Surana he would actually believe that he really is the Maker's chosen and speaks for Andraste. He would marry Cassandra Pentaghast for political reasons. He would ally with the templars and use them to hunt down every single rebel mage/apostate he could find. He would not allow Dorian or Cole to join the Inquisition. He doesn't have much love for the Wardens, but their treaties are useful so that could be the only reason why he would allow Blackwall to join. If he ever found out about his true identity he would let Orlais have it's justice and Thom Rainier would hang. He would not recruit Sera. He sees the Red Jenny as criminals, thieves and murderers, nothing more. He would not recruit Hissrad - he wants nothing to do with qunari heretics and spies. He would be extremely suspicious of Solas who in his eyes is an apostate, but would probably respect Madame Vivienne who could easily charm and wrap him around her little finger. She would likely be the next Divine.

Interesting concept. Sadly, my answers will be short and to the point.

My Hawke in DAO wouldn't romance anyone.

My Warden would most likely fall for Cullen in DAI.

My Inquisitor would remain single in DA2.

My main Inquisitor is gay and an elf, so naturally Zevran would have been an ideal fit for him in DAO. He is also an archer assassin, so they would complement each other's skills nicely. A pretty deadly team. Zevran is my favourite romance from DAO so I generally have to come up with a good reason not to romance him. So my female Hawke mage would probably have romanced him too, considering she romanced Fenris in DA2.  Still there is the possibility that Alistair would have won her heart before Zevran appeared on the scene. 

For much the same reason as for Zevran, if either of my other characters had been Hawke they would have ended up with Fenris, because he is my favourite romance from DA2. Mostly due to my preference for elves but I found I couldn't really see Merrill as a romance. My female city elf Warden would never romance a human, for obvious reasons given what happened on her wedding day but also because of the way Loghain betrayed the memory of the night elves who helped him and Maric.

If my main Hawke had been the Inquisitor, then she would likely end up with Cullen, seeing as there is not a heterosexual elf option for her.
My main Warden is a female city elf, so she might well have ended up with Solas, although the relationship might be rather prickly but I think ultimately she would win his respect. She would definitely have not got on well with Sera even though she is not particularly devoted to all things Dalish. I just know there is something about Sera that would really rub her up the wrong way. Raven Tabris is a very feisty elf. If she had romanced Solas, though, she would be the unforgiving sort after the way he treated her and what he intends to do. She'd hunt him down in the hope of stabbing him with her family heirloom, Fen'Harel's tooth.

Warden Cousland
DAII: She'd go for Anders. She would know him from Awakening, and the switch between virginal templar and experienced mage would be interesting as well.

DAI: I had difficulty choosing between Alistair and Leliana in Origins, so, since Alistair died, my Cousland would definitely ask Leliana if she would still have her. She'd probably feel some attraction towards Cullen, but that would be because he'd remind her of Alistair, and not because of the person Cullen really is, which would make her feel guilty and sad. She'd stay far away from him.

Hawke
Origins: Hawke would go straight for The Pearl and look up Isabela. The Archdemon would win the war.

DAI: After the whole Anders debacle, my Hawke was properly pissed off. She'd want something nice and quiet with Cullen. Partly out of spite.

Inquisitor Cadash
In Inquisition she had relationships with Blackwall and Josephine, but both just didn't work with the character. Now I like to headcanon that she flirted with Harding even though there was no more opportunity to do that.

So, accordingly, in the other two games, my Cadash would be pining after the dwarves she can't have - Sigrun and Varric.

DAO:

My Isabela-romancing Hawke would have likely gone for Zevran. They already slept together in DA2 so why not. He's got some of the same qualities that attracted her to Isabela, and she'd have been intrigued by the whole failed assassination attempt thing, enough to at least initially give him a roll in the hay for kicks. There'd definitely be another threesome at The Pearl.

My Inquisitor would have fallen hard for Morrigan. They're both mages, but Morrigan's an apostate, cool and confident and not at all like anyone the Inquisitor's ever known. Sadly, my Inquisitor is also female and therefore would ultimately be foreveralone. Poor Inquisitor.

DA2:

My Warden was a romantic disaster who ended up with no one, but in DA2 I could see her romancing Fenris. He's got a dry humor and pragmatic outlook on things that she'd have appreciated. She'd have remained broken up with him after he left, though. 

The Inquisitor would have definitely gone for Merrill. My Inquisitor is a bit of a chatterbox and curious to a fault, especially about weird magical things, and Merrill's funny and bubbly and passionate about the things she cares for. I can see them growing close over nights talking shop about magic or stories about the Dalish and the Circle.

DAI:

My Warden would have pined away for Cassandra, only to be thwarted by her insurmountable straightness. She may have a bit of a flirt with Cullen out of homesickness for Ferelden, but that's about it on the romance front.

Hawke would probably flirt with Sera but ultimately Sera is just too young for her - she's better off with Dagna. Probably Iron Bull in the end.

Hmm...

Warden, Surana Mage
(Original LI: Alistair)

DA2: She flirted with Anders and they had a shared sense of humor, just like with Alistair, and were both "rawr templars" so I'd say Anders.
DAI: Is this assuming that the origin stories are still intact? Because it would be Cullen. If not... still Cullen.   Or maybe Blackwall because she admired Wardens, and would probably enjoy trying to make him laugh.

Hawke, Sarcastic Mage
(Original LI: Anders)

DAO: Her level of snark might only be matched by Zevran? (She'd be a better match for pre-Justice Anders, honestly. I can't separate these two very easily. )
DAI: I wish I could say Dorian because their combined wit and rebelliousness would be a hot magical mess. (So I'd say for my male sarcastic mage this would be perfect.) But, since she's a lady... Hm. Bull? Seems like they might get along well -- though I'm not sure how they'd mesh in the bedroom. 

Inquisitor, Lavellan Mage
(Original LI: Solas)

DAO: I'm leaning toward staying single here...
DA2: Probably Fenris since she liked the broody mystery of Solas.   Then again she's enthralled by magic and spirits, so... Anders.


Now I'm going to be thinking about this with all my other characters...

Alistair, Anders, and Solas? Were they the first romances you did in the games? That must've been traumatic. 

(EDIT: Changed the wording a bit because I sounded judgmental and that's not what I meant.)

I have a lot of PCs in DA. Let's see if I can get them all...

Wardens (I have 10 atm):
My m!Mahariel (romanced Leliana) wouldn't really go for anyone in DA2. Merrill would be the closest bet, but her sees her as too much of a friend that anything more wouldn't feel right to him. As for in DA:I, he'd probably go for Cassandra. He's a bit of a romantic.
My m!Aeducan didn't romance anyone in DA:O, and I can't reall see him romancing anyone in DA2 either. As for DA:I, he'd probably go for Harding.
My f!Surana (romanced Alistair) might see about Sebastian in DA2, but in the end, she probably wouldn't be with anyone as she wouldn't really like Anders' extremist views and she wouldn't click with Fenris. In DA:I, I can definitely see her going for Cullen.
My f!Brosca (no romance) would probably try pretty hard to get Varric in DA2. Besides that, probably no one again. In DA:I, I could see her trying for IB.
My human-hating m!Tabris (no romance, but I ship him with my angry f!Lavellan in this world-state) may be interested in Merrill in DA2, but he may see her as a bit too naive for his taste. Not fully sure which way he would go. He probably wouldn't be with anyone in DA:I.
My f!Amell (romanced Leliana) would probably have difficulty deciding between Isabela and Fenris in DA2. I can see her going with either of them. In DA:I, I can see her showing some interest in Sera, before deciding on Josephine.
My f!Mahariel (romanced Zevran) would probably go for Fenris in DA2. As for DA:I, she might go for Solas, but I'm not entirely sure.
My f!Cousland (romanced Alistair, though I headcanon that she's bi) would have to decide between Fenris, Merrill, and Isabela in DA2. With Isabela, she might just go for a fling, then decide on Fenris. When he leaves her (because we all know what happens), she'll end up finding comfort with Merrill. As for DA:I, I can definitely see her going for Cullen.
My m!Surana (romanced Morrigan (no, I'm not biased towards playing as elves >_>)) may go with Isabela or Merrill in DA2 (Isabela for fun, Merrill because of her interest in the eluvian). In DA:I, I can see him going for Cassandra.
And finally, my f!Tabris (romanced Alistair (I'm also not biased towards romancing Alistair >_>)) would probably go for Fenris in DA2. In DA:I, she would probably go with Cullen.

Hawkes (8 atm):
My mage Diplo!m!Hawke (romanced Merrill) would probably go with Leliana in DA:O and either Casandra, Josephine, or Harding in DA:I.
My dual-wield rogue Snarky!f!Hawke (romanced Anders) would probably go for Alistair in DA:O and Cullen in DA:I.
My S&S warrior Diplo/Snarky!m!Hawke (romanced Isabela) may go with Morrigan in DA:O, bit idk for sure. As for DA:I, he may go with Cassandra, but maybe Harding.
My blood mage Diplo!f!Hawke (romanced Merrill) would probably end up romancing Zevran in DA:O, and possibly end up with IB or Harding in DA:I.
My archer rogue Snarky!f!Hawke (romanced Fenris, and my only pro-Templar Hawke) would probably end up with Zevran or Alistair in DA:O (Zevran is more likely), and probably romance IB in DA:I.
My two-hander warrior Snarky!m!Hawke (romanced Merrill (named him Mike for lolz)) may have romanced Leliana in DA:O and Cassandra or  Josephine in DA:I.
My second dual-wield rogue Snarky!f!Hawke (romanced Isabela) would probably romance Leliana in DA:O and Sera or Harding in DA:I.
My current Hawke is a Snarky!m!Hawke mage.  Haven't decided on who to romance yet with him, tbh.

Inquisitors (6 atm):
My dual-wield Assassin f!Lavellan (romanced Solas) may romance Alistair in DA:O, but I'm not entirely sure about that.  In DA2, she might romance Fenris.
My two-hander Reaver m!Adaar (romanced Cassandra) would most likely romance Morrigan in DA:O.  As for DA2, he'd probably not romance anyone.
My archer Tempest f!Cadash (romanced IB) would probably romance Zevran in DA:O, since she's mostly looking to have fun.  Probably no romance in DA2, but she would be best buds with Isabela
My Rift Mage m!Lavellan (romanced Josephine (ok, fine, I've biased towards playing as elves >_>)) would probably romance Leliana in DA:O and Merrill in DA2.
My angry Knight Enchanter f!Lavellan (no romance, but I ship her with my human-hating m!Tabris) might end up romancing Zevran in DA:O, but I'm not entirely sure on that.  As for DA2, probably no one.  Fenris is a maybe, but she is a proud mage, so...
My S&S Champion (romanced Sera) would probably romance Leliana in DA:O and most likely romance Isabela in DA2.

Well, that's all of them, for now.  sry for the large post >_>