Leon as your bodyguard...
Leon tries to keep it professional, really he does. However he finds you amusing, relatable and so easy to get on with, this means that the line between bodyguard and friends or more becomes extremely blurred.
He's kind of bossy, but it's for the best. You both like some of the same things, so living together isn't hard, however he does get antsy over small things like you opening windows or trying to go outside on your own.
He accompanies you everywhere, he becomes a different person when your safety is involved, he's strict and keeps you close, often having a hand on your arm or pulling you away when he thinks something is up.
Leon finds himself enjoying being around you, his feelings get too personal and he knows it's bad. He tries to back away, but you notice and ask him what's wrong, he just shakes his head and blanks it out.
After one too many drinks you admit your feelings for him, Leon is shocked yet he tries to hide it, telling you it can't happen and nothing can happen between you both.
But you kiss him, and it's game over for his facade, he pins you down and shows you just what you do to him, but before it can get too heated he pulls away, saying your just a job, and that's all. You don't believe him, breaking his resolve he mutters a "fuck" before crashing his lips to yours once more.
After that, things change between you both. You become more of a couple, sleeping together and sharing food, snuggling and bathing together. You both keep it a secret though, but gladly tease each other in public, pouting your lips or him murming things in your ear.
Leon knows this could cost him his job, but he's way too in love to care, he's just worried about the repercussions when it does eventually come out. When when it does, he fights for you and doesn't back down, even when others try to split you up or take you away.
Leon will burn down the world for you, he's no longer that rookie cop who wants to save the world, not when his whole world is you.