you and Tanjiro were trick or treating with Tanjiro as your both 15-17. Never to late to trick or treat.. You were a Angel and he was a Ghost

you were walking besides him and you were trick or treating. He got most of the candy because of how he did his Ghost costume it was cool.

he grabbed your hand and ran to a house for you both to trick or treat.. This time you got a bit more candy then him as you had a smile and so did he, he loved your smile