Female Lavellan Mage + Sera = contrast of elves from two completely different walks of life, with different values and personalities. The awkward, studious First with a gregarious wild child. Lavellan's fascination with city elves will probably kick-start things, if Sera isn't forward. Both have a heart of gold. Seems like a winner.
Male Lavellan Rogue + Dorian = has an element of being 'on opposing sides' due to Tevinter and Dalish. Also the smaller one being a frontline fighter while the bigger one is the squishy mage is a personal favourite combo of mine. I'm expecting my Lavellan to be caught unawares by Dorian's charm and fall pretty fast.
Female Adaar Mage + Josephine = big, scary Vashoth apostate with the elegant, noble diplomat. Adaar will probably attempt very awkward courting and 'traditional' romantic things, and hopefully it will win Josephine's heart and all be very cute.
Female Cadash Rogue + Blackwall = surface dwarf with a Warden, who probably knows more about the Deep Roads than she does. Cadash is the oldest age possible (45?), pretty gregarious and full of life, wanting Blackwall to live his life to the full before his Calling. Will probably be tragic, but damn if he won't have a good time first.
Female Trevelyan Warrior + Iron Bull = noble lady warrior with a heathen brute. Life contrast again. I'm looking forward to her possibly bringing him to fancy parties, especially if she's recognised by any fellow nobles. Both like fighting and drinking. I want to explore mixed race relationships with Qunari, and human seems a safe bet.
Male Lavellan Warrior + Cassandra = surly, proud Dalish warrior falls for a fierce shemlen lady. Not sure who'll get things going, since he's pretty tsundere, and I can't see Cassandra coming onto him. Probably affection born from growing respect. Once they're in a relationship, I expect fierce loyalty, awkwardly cute moments and whatnot.
Female Lavellan Mage + Cullen = different walks of life again, different faiths. It's on an Amell + Leliana playthrough, so interesting possibilities and contrasts there. Not sure yet if that combo will work on a personal level, if they're too different but I'm interested to find out. Romancing him as a Dalish mage could be very interesting.
Female Lavellan Rogue + Solas = Dalish hunter with huge respect for mages, practical and adoring of nature. Powerful elven mage with a lot of knowedge about elven ruins and whatnot. She's probably one of my more contemplative and intelligent Inquisitors. Depending on his reasons for being f!Dalish only, it could be a perfect match.
(Yes, I like Lavellans a lot)