Theophylline molecule had taken his cousin Caffeine down to the stirrer bar for a drink. They were just settling in for the evening, enjoying their cocktails and conversation when in walked an extremely attractive methacrylic acid, who pretended she hadn't seen them.
"Cor!", said Caffeine excitedly, then
"Hey! Didn't you used to have a thing with her? What happened?"
Theophylline sighed,
"It, well it was complex ‒ you see all the time I was with her....