The player character is a blank slate nobody, and there's no reason why anyone would follow them as the leader - but that would be okay if our companions were also fairly average people with their own things going on, but nothing too dramatic. As it is, all of the companions have epic edge-lord back stories that are so extravagant and ridiculous that the very idea of them choosing to follow our character's decisions is laughable. It's a really silly flaw in the current design. The developers love their mary-sues, though, and don't really seem interested in listening to other opinions on the matter.
Maybe you just have a better tadpole than anyone else? If you ignore Shadowheart she says she felt drawn to seek you out (and stab you but you can talk her down and invite her to join you).
Like, of all the Tadpoles, your tadpole was the...tadpoliest? Like its Tads, are just huge. And that's how Tadpole hierarchies are established. You just whip out your Tads.