Severus Snape was absolutely obsessed with Froot Loops.
Severus was quite unlike most wizards; he didn't try to steal Trix from first years, like fellow Slytherin Lucius Malfoy enjoyed doing; nor was he cuckoo for Cocoa Puffs, like that damn James Potter and his friends. Instead, he was fond of Froot Loops.
Very fond, in fact.
Each day, for every meal, the young Slytherin ate spoonful upon spoonful of the artificially-flavoured, multicoloured rings. He knew eating nothing but Froot Loops would eventually lead to his demise, but he didn't care; Severus longed for the sweet embrace of death, anyway.
Severus constantly thought about Froot Loops and when the next time he'd eat them would be, even though he always knew the answer. All he ate was Froot Loops, and all he drank was the milk from the numerous bowls of Froot Loops he ate every day. Froot Loops dominated his mind, and once he even had a wet dream involving the overly sweet cereal.
Like 99.9999999999% of everything else he enjoyed, Severus's obsession with Froot Loops had something to do with Lily Evans, the love of his life.
It all started one morning in the summer of 1970. Severus's parents were too busy fighting to feed their son anything for breakfast, so he went hungry for the day.
When Severus went outside to talk to his friend, Lily, she noticed that Severus looked extremely malnourished, and could tell he hadn't eaten all day.
"I'll be right back, Severus." With those words, Lily took off to her own house. Severus wondered what she had left for, until the redhead returned with a small plastic bag filled with an unfamiliar, colourful cereal.
"I'm not sure if you like sweet things, but you need to eat something." Lily handed the bag to Severus. He reluctantly took a green Froot Loop out of the bag and ate it. To his own surprise he enjoyed it immensely, devouring all of the bag's contents within a minute, simultaneously impressing and confusing Lily.
Because he knew he wouldn't always be able to have Lily bring him plastic bags of fattening cereal every day, and since his parents were both neglectful and not well-off, Severus got a job so he could buy the cereal he enjoyed, despite only being 10 years old.
Although Hogwarts served all kinds of food including delicious but unhealthy children's cereal, Severus's parents still could not buy the cereal when he was home for the summer; and on top of that, they found Froot Loops to be absolutely disgusting, so even if they were well-off and didn't fight 24/7, they'd still refuse to buy the cereal; therefore, Severus took different jobs each summer so he could eat the only food he enjoyed.
Even in adulthood, Severus did not kick the habit of exclusively eating Froot Loops. The rest of the Hogwarts staff stared at him every morning and evening for only eating sickeningly sweet cereal; Dumbledore had unsuccessfully tried to convince Severus to eat something other than Froot Loops on countless occasions.
The students, however, were completely unaware of Severus's unhealthy diet until one morning, after a certain pair of red-haired twins slipped something into his cereal, which caused Severus to, as one would put it, "freak the fuck out", and accidentally spill his cereal, showing the entire student body that he, indeed, ate Froot Loops for breakfast every morning.
Severus never heard the end of it.