Have a summary/drabble/head canon:
In the beginning, Barry Allen wanted to bond/mate with Iris West, but she fell in love and chose Eddie Thawne instead. He was happy for them, but Barry couldn’t help growing lonely as time passed, and one day he visits one of their holy temples and prays to find his true mate soon. Almost immediately after, Barry finds the unconscious body of a winter fairy.
This is Leonard Snart, a notorious thief with at least a few bounties if not a massive debt on his head from the royal family of the winter fairies. Barry takes him in, and nurses him through his injuries, something a lot like love growing between them. Len is quite evasive in regards to how he got injured, but he eventually confesses to Barry about his crimes and how he was escaping bounty hunters and trained soldiers alike. He understands if the other fairy wants him to leave, as having him around is dangerous.
Yet that isn’t what Barry does, instead he offers up a family heirloom: a rare blue pearl. This way, Len can buy himself out of debt with the royal family and be free to do as he pleases. Secretly, he hopes Len would choose to stay with him, but he won’t say it out loud and pressure Len.
Len is touched, seeing this gift for what it really is, and promises to return as soon as he’s settled everything with the royal family. So with a hopeful heart, he leaves to do just that.
Unknown to both, Eobard Thawne schemes for Len’s demise. He had encouraged and supported Iris and Eddie’s courtship, b/c he wanted Barry to himself. He also scared off any other potential suitors from ever approaching Barry, and fully intended to start courting him that day after Barry prayed at the temple. But he hadn’t expected the other fairy to find Len. Now that he’s away, Eobard assists some other fairies, (bounty hunters), to find and kill Len.
Time passes, and Barry starts to worry that Len got hurt, thrown in prison, or worse, chosen to stay and forget all about Barry. Then, it’s discovered that some bounty hunters had gone after him, having been told where to look via Eobard. Beyond worried and now desperate, Barry leaves to the winter lands to find Len.
His wings weren’t meant to endure the cold, and despite what clothing he’s wearing, it isn’t enough and Barry winds up collapsing at some point, nearly frozen. This is how Len finds him, as word spreads about a spring fairy flying around the area. He immediately takes Barry to his private den to recover.
It’s during his recovery that Barry discovers Len still has the pearl, b/c he didn’t want to part with it over a stupid debt, not when it means so much. Instead, he’d been doing honest work so he could pay off the debt he’d created. He invites Barry to stay with him, agreeing to leaving once all things were settled, cause it was easier for both of them to live in the spring area rather than the winter one.
By the time they return, the two of them are bonded, having had a private ceremony with Len’s friends and family, and are expecting.