The Confluences seem random, but they seem to pull in exceptional people, with a fair number of metahumans or metahuman-adjacent individuals. There’s very little published on the nature of the anomalies. Likely deliberate with the society’s technological level.

It’s likely something to do with vibration frequencies of your universe. A Confluence uses up a massive amount of energy. The energy has to come from somewhere. It could siphoning it from elseworlds. In which case, Gotham City is obvious. It’s been steeping in metaphysical energies for centuries. Not to bring in quantum theory, but it’s obvious you’re a nexus point.

[ A beat. ]

Or did you mean here, at the store?