Adam

Most dens built by fae progenitors are hung off the sides of cliffs, or off of the trees the fae dragons harvest sap from in order to build their homes. This places them in a location out of reach of most predators, after all - and the few predators that can reach generally know better than to target such dens.

But Adam knew that his clan would never have only just fae dragons in it. And he had seen old dens fall to the ground or into the ocean, pulled down from their moorings by the weight of the structure. So, planning for the future, he and Heries built an audacious den: one that barely relied on the cliff at all, extending down into the ocean and making the most of their elemental alignment by using the real estate available there.

There was a reason why no other fae clan had tried it before, however: the meren.

Although Adam took to the water like he was born to it, he wasn't suited for physical combat and a new lair was difficult to build and defend at the same time. As inspirational as the dream of having an underwater lair that could expand to meet the needs of its members and continue standing for decades was, it might well have ended quickly if they hadn't had an influx of new clan members who were well-suited for defending the territory.