Simon didn't know what to say to her. She was only three years old, he didn't want to say anything until she was older again. He had already completed the antidote and only went upstairs to see what was the matter with Jennifer. He was glad when he found out she was okay, she was just a little upset. He went downstairs and brought her with him. She drank it in silence, but then managed to knock some over and it fell into Alvin's mouth somehow. Simon didn't notice and since Simon didn't care Alvin didn't either. They watched as Jennifer grew up and became 15 once again, and somehow her clothes grew with her body. Simon handed her glasses to her and she put them on with satisfaction. Right before Jennifer left Simon called out, "I love you Jennifer. Merry Christmas!" She smiled and handed him and Alvin 50 dollar bills.
"For all the trouble I caused." she explained. Then she pulled Simon close to her and they shared a long kiss.
This ending is probably terrible, and I wanted to do it on Christmas, but I didn't know how to word this out and this was all I could come up with. There's probably be a sequel to this about Alvin growing older since he had some of that antidote. Happy New Year!