[Lively and cheerful little sun & gentle and possessive]
[1v1+childhood sweetheart+He+age difference of three years]
He has been her "shadow" since childhood, habitually protecting her and helping her solve all her troubles.
Everyone thought they were just brother and sister, even she believed that.
It wasn't until her first time with her boyfriend that his calm façade was completely shattered, and she didn't see clearly the unspoken, hot desire for exclusivity in his eyes.
