This is the answer to the "19,000 Prompts, 500 Words, One Week" Challenge.
Red
The first thing Arthur Weasley, third son of the house of Weasley, noticed when he first laid eyes on Molly Prewett was that her hair was the most fetching shade of red. The second was that she had two older brothers.
It was the latter fact that made him hesitate in his approach of his yearmate for a while, but Arthur Weasley was not a Gryffindor for nothing and he managed to work up the courage to not only approach Molly, but also face her brothers down in a stare down.
Only years later would the twins confess to him that they had not only been checking whether he was good enough for their baby sister, but also if he would be capable of surviving her wrath. When he had first started courting the young woman, this statement had confused him, but when the confession was made Arthus simply nodded sagely, fully aware of the fact that the scariest one out of the Prewett siblings weren't the twins, be it alone of together, but their younger sister who had a temper that could not be described with fiery, but rather reminded one of a very active volcano.