Léon using a pig-themed oven mitt as a Hand Puppet to cheer Mathilda up after her family is executed.
Is it weird that this troper considers Léon's ultimate decision not to just Mercy Kill Mathilda as one?
Not at all. He's been trained pretty much his entire adult life to quash any shred of emotion he has, and when he wakes up to kill her, he seems to have a "What the hell am I doing, letting her get close?!" look on his face. He gets the gun, screws on the suppressor, puts it to her head... and just snaps out of it. Despite what he is and what he's done, he's still a human being, and she's still a little girl. What's more Heartwarming than that?
Leon spraying Mathilda with a water bottle while she runs around their apartment. Their antics eventually cause a closet door to fall off, eliciting laughter from the both of them.
Léon and Mathilda's good-byes.
Mathilda digging up some soil and placing Leon's Companion Cube potted plant in the ground, which she addresses by his name.