Teach: son of Rocks, fought in Rockyport, and became the leader of Hachinosu (Rocky Port event), an island with a skull carved into it in a very specific rocky shape. God Valley also has a specific rocky shape, and the island's geography resembles the Red Line. I don't understand why people tell me it's crazy to believe that Blackbeard might have the power of the Earth God, or that this could even be the true nature of Edward Newgate's gura gura no mi (that's another hypothesis, but I believe in the third fruit). This hypothesis is quite plausible in my view.
Another interesting thing is the possibility that Garling intentionally had children with a woman from the Davy clan for some "warlike" interest, given the clan's nature. And the name of one of his sons is Shamrock.