Darcy/Jane/Thor
Darcy had always been a little bit anxious about her soulmates. She had two. This wasn't exactly common, and she tried to keep it as under wraps as she possibly could. One one of her soulmarks wrapped around her wrist, a completely unhelpful, “Darcy Lewis?” in tiny, neat printing. The other was what she had identified as Norse runes, running down the outside curve of her hip. That one was easy enough to keep hidden, or pass off as just a tattoo if someone happened to see it while she was swimming. Darcy didn't do a lot of swimming.
But while everyone else who had them was talking about marriage and babies and things like that, Darcy just kinda smiled and went along with it. Marriage wasn't... No. A lot of internet searching had helped Darcy reveal that she was aromantic. Platonic soulmates happened, but they weren't common. And what were the chances she had two?
Which was why she'd been very relieved to meet Dr. Jane Foster. Jane was her best friend, and the match to the soulmark around her wrist. Jane was not aro, she was actually ace, but they were definitely platonic soulmates. And Jane's other soulmark, while not a direct match to Darcy's, was definitely Norse runes, written in the same hand.
And then Thor had dropped quite literally into their lives, and was obviously the match to both of their soulmarks. He and Jane seemed quite happy to fall in love with each other, which was pretty fucking fantastic. And Darcy sort of kept to the outside, letting them do their thing. Because he was hot. He was, like, panty-melting hot. Darcy wanted nothing more than to have him toss her over his shoulder and carry her somewhere to have his way with her. Repeatedly. But... Well, it was complicated. Obviously. The fact that they were platonic soulmates didn't uncomplicate it at all.
He left for a while, came back two years later. He and Jane had their big reunion moment, which was awesome, and then it was just the three of them left in the tiny flat.
He kept looking at Darcy, smiling. And she figured, you know what, fuck it? Better to just get it out in the open.
“So, I know you two are all in love forever, which is totally awesome, but, like... Does that mean sex is off the table for us?” She tried to pass off casual nonchalance and probably catastrophically failed.
Jane laughed, of course. She'd agonized about it at length to Jane, who'd gone with, “Well, just talk to him about it.” Jane didn't have a problem with the idea, which helped.
He looked at her, blue eyes moving over her with an intensity she hadn't seen before. “No. Is this something you desire?”
“Yes?” That came out as more of a question than Darcy really wanted, but she nodded for emphasis.
The intensity in his eyes made her shiver. He glanced over at Jane, and she nodded, and then he was up off of the kitchen chair and moving towards where Darcy was standing beside the wall, arms folded. He looked down at her for a only a second or two before he reached out and grasped her waist, lifting her off the floor and onto his shoulder.