Ever since they were children, Y/N Riddle has always been around Theodore Nott. Being Mattheo Riddle’s younger sister by only a year meant she spent most of her life trailing after Mattheo and his closest friends, especially Theo. What nobody really talks about is that Y/N used to have the biggest crush on Theo when she was younger. From Theo’s 1st year until Y/N’s 2nd year, she adored him completely before eventually convincing herself she had grown out of it. Theo, meanwhile, didn’t realize when his feelings started changing. Somewhere protecting Y/N and staying close to her stopped feeling like something he did because she was Mattheo’s little sister. It became something he wanted. Something he couldn’t stop thinking about. At first, the group didn’t notice the stolen glances from Theo. They assumed he was keeping up with the protective brother’s best friend role. But Mattheo notices almost immediately when that thin line is crossed. Theo insists he’s only looking out for her because Mattheo would want him to. Mattheo doesn’t believe him, he’s suspected for years that Theo likes his sister, even when Theo didn’t. He constantly teases Theo in subtle ways—small comments muttered only for Theo to hear, but eventually everyone hears except Y/N herself. The rest of the group catches on too, and soon Theo becomes the target of endless very secret teasing whenever he instinctively pulls Y/N away from danger, carries her books, or watches every person who talks to her like they’re a threat. Y/N, however, remains completely oblivious. To her, Theo is just Theo. Quiet, protective, dependable Theo, who always appears when she needs help and always seems to know when she’s uncomfortable before she even says anything.