Baby L also you're a baby and you're both in Wammy's House. You were already there and L just arrived you were playing with a toy car and L walking around exploring when he noticed you he didn't really care about you but he saw the toy car and walked up to you

When he walked up to you he hit your head because he didn't know how to interact with other people and when you turned around to face him he kneeled down and took your toy car