supercoldflash 50 arranged marriage and 9 dance with some 95 sleep intimacy?
So, Barry is minding his own business one day when suddenly there’s a great big old booming voice demanding to know where “the Flash” is, so he goes to the city center and finds -
See, apparently the reason Barry couldn’t find Kara’s Earth-1 doppelganger is because in Earth-1, Krypton…well, no Krypton did blow up, but someone actually bothered to make a plan and there’s a colony ship of Kryptonians zipping around.
It was onto one of these ships, in fact, that Leonard Snart got spat out off a black hole connected to the Oculus.
And, well, once /on said ship, he may or may not have decided to save his ass from getting pulverized by swearing up and down that there’s someone on Earth capable of beating a Kryptonian in a footrace.
Now, the surviving Kryptonians are very interested in this, as they rescued primarily their own family members from destruction while thoroughly forgetting the concept of genetic diversity (they were engineers and physicists, not biologists, so sue them), so someone Equal to them sounds great, so Zor-El and his daughter Kara go to Earth with Len to confirm this.
When faced with a “race my daughter or I kill you, Len, and possibly destroy this planet for kicks” threat, Barry agrees to the race and, knowing Kara as he does, is able to win, albeit just barely.
Since Kara is the fastest Kryptonian, that’s very promising: Barry is indeed their equal.
So clearly that means he needs to marry Kara and have good, strong Kryptonian babies.
Do not be concerned, Earthling! In understanding the limitations of such puny human bodies, as learned from Leonard Snart, they are willing to bind Kara to both Barry and Len, since Len seems to still have those weird Oculus powers and they’re kinda into seeing if those are hereditary, and anyway two Earthlings to one Kryptonian appeases their sense of arrogant superiority.
“Don’t look at me,” Len says. “This is out of left field for me, too.”
“You don’t actually have a choice here,” Kara says, rather apologetically.
Cue a marriage and an awkward moving-in-together sequence and some scorchingly hot sex, but they don’t really start getting together until the day Len decides to teach them both to dance.
They’re awful at it, but he persists until they’re all laughing together.
That’s the first night they actually sleep together, just sleeping.
After that, things get better.
(but boy is it awkward when Supergirl-canon Kara finds out)