At Lily and James' wedding, the only parent attending was Lily's mum as James parents and her husband had died recently. Lily's mum sank into depression before the wedding and she didn't even want to go. A week before, Sirius Black turned up on her doorstep, in a suit. He then asked her to be his date to the wedding, trying to cheer her up. Her and Sirius danced together all night and when he took her back to her room she told him,"Sirius you are a lovely young man and tonight you made an old woman smile." Before kissing him on the cheek. In the morning they found her dead in her bed, having died peacefully in her sleep. They found her with a small smile on her face.
A/N this is meant to be a mother-son kind of thing, not creepy.