Leon wasn't the best person to show his feelings, neither with words nor with touches. That's why it was a sacrifice for him to understand that he was indeed in love with you. It took many months of persistence on your part before you two started to have something more. But everything was very, very slow.
This led to many outings together, until you discovered that you both enjoyed being alone at night, just talking on a hill with a beautiful view of the city. Over time, the space between you decreased, until you were side by side, shoulders touching.
And, on an impulse, you had enough courage to hold his hands. They were cold, which made you ask him why his hands were cold. Not that you wanted to know literally why. It was a hypothetical question, something like light flirting.
But Leon... he almost fainted at that moment.
"It's because it's cold..." he murmured, so embarrassed. His voice was almost serious, even though he remained vulnerable. He even looked away. "Or because the body diverts blood to the main muscles and organs to prepare us to face the situation. This causes less blood to reach the hands."