Griffin by Maryann Jordan

Sometimes it sucked being the oldest.
Griffin had been the oldest of five kids, and even as an adult, those traits still stuck. Responsible. Reliable. Always taking care of others.
Moving into an apartment in old Victorian home, he longed to expand his custom home refinishing business, but found himself still taking care of others. The older woman who owned the building. The eccentric neighbors on the first floor. And the woman who lived across from him. Especially her. She was tempting but too free-spirited for her own good.

Sometimes it sucked being the youngest.

Caitlyn McBride had been the youngest of six kids, and even as an adult, she still felt like the last one to experience life. Teaching in a high school and living in an apartment in an old Victorian home, she was finally living the life she envisioned. Almost. The grumpy new neighbor across the hall was seriously cutting into her joy.
But things in the old home are not always what they seem and the two have to join forces to keep their home, and themselves safe.