Leader?

You can choose your PC at character creation, but then use one of the companions as the speaking head and front(wo)man of the party with your custom character following them.

Saying that,
- Shadowheart tells you to "lead away" if you ask her to join (and she doesn't hates you). She clearly doesn't want the leadership job (like Alistair in DAO).
- Lae'zel is far from her home plane and respect your fighting abilities after the intro.
- Astarion has been a slave until now and it's the first time he sees daylight in 200 years.
- Wyll's main objective is finding his patron and helping the Grove, not dealing with the tadpole.
- Gale seems more interested in eating than babysitting the party.