One common theme is their partnership. They often team up in fanfics, whether it's for a heist or to fight against a greater evil. Their different skillsets - Sara's combat abilities and Snart's cunning - make for an interesting dynamic.
Rather than specifically seeking lemon fanfics (which are not in line with most ethical and community guidelines), you could look for fanfics that explore the relationship between Sara Lance and Leonard Snart in a more platonic or action - oriented way. For example, some fanfics might focus on how they team up to face a common enemy, or how they come to respect each other's skills. Check out well - known fanfic communities and look for fics with high reader reviews in this regard.
Love and redemption are also quite common. Maybe Snart, who has a more morally ambiguous past, finds a kind of redemption through his relationship with Sara. And of course, there's the theme of trust. Since they both operate in a world where trust is hard - earned, fanfics might focus on how they build that trust with each other. There could be stories where they start off as reluctant allies and gradually become more than that.
A possible plot could be set in an alternate universe. Leonard and Sara are living a relatively normal life when she gets pregnant. But then, elements from their original 'universe' start to seep in. Enemies they thought they left behind start to target them because of the baby. They then have to use their skills and the help of some new friends they made in this alternate world to protect their family - to - be. It's a story of love, danger, and new beginnings all rolled into one.
Yes, there are likely some non - explicit fanfics. Many fanfic writers focus on the relationship between characters in a more platonic or emotional way. They might explore their adventures together, how they grow as individuals in each other's presence, or the development of a deep friendship. For example, they could write about how Sara and Leonard team up to face a common enemy and how that experience changes their view of each other without involving any sexual content.
One idea could be a time - travel related pregnancy. Maybe they get stuck in a time anomaly where Sara discovers she's pregnant, and Leonard has to figure out how to get them back to their own time while protecting her and the unborn child. It could involve some emotional moments as they both come to terms with this unexpected situation.
Friendship is a big theme. They might start off as reluctant allies but grow to become true friends. For example, they could be on a quest together and along the way, they learn to trust each other more and more. Also, the theme of family could be explored. If they are part of a larger group, they could form a sort of surrogate family with the other members, and their relationship within that family - like structure could be the focus.
You can start by looking on fanfiction.net. It has a large collection of fanfics for various fandoms, including those related to Leonard Snart and Sara Lance. Another option is Archive of Our Own (AO3), which is known for its wide range of fan - created works and has a great tagging system to help you find exactly what you're looking for.
One idea could be that they have to protect their baby from a time - traveling villain who is after the baby's special powers. Another could be that they raise the baby in a world where they are trying to balance their former criminal and vigilante lives.