If there was one thing the Wizarding World needed, it was a good bookstore.
It wasn't that Debi had anything against Flourish & Blotts - far from it! She browsed there regularly, and the basic books on magical history and theory had helped her immensely as she adjusted to her new life, even if the Muggle Studies books were hilariously wrong. But a bookstore with soft music, and maybe a cafe, and chairs to curl up on while she checked out a new release - that didn't seem to exist in the Diagon Alley.
She assumed that Haven Books would be more of the same, but the promise of free tea was enough to drag her away from checking out the latest fashions in Gladrags (which were better than Madam Malkin's but still dowdy by Muggle standards, especially the "women's" and "maternity" sections - no wonder Severus had decided on drag!) and into the new store.
Where she fell instantly in love. This was a bookstore, from the polished shelving to the soothing colors to the comfy chairs. All it needed was a fat, fluffy cat drowsing in the main window and it would be perfect.