I still think she's supposed to be an exception to the whole 'leaders' thing and isn't the leader of the Red Jenny group (they might not have a leader at all).
Sera doesn't seem the type to lead from what we know about her.
Considering that, I'm curious why the Inquisitor would even recruit her in the first place? Like, what's her selling point? "Hey, I'm a lot of fun!" ...well, that might work since most others are a stick in the mud xd
Sera might be 'the thing that would not leave'. She'll just be like 'I'm going with you!' and no matter how much you try to get rid of her (short of killing her), she just won't leave you alone.
I'll make sure to have Cassandra along when we recruit her (I'm going to bring Cass everywhere anyway). She's bound to disapprove and that will be good enough for me!
Sera: So yeah, I can shoot a bow and pick locks.
Inquisitor: I don't know...
Cassandra; We have no need for the likes of you.
Inquisitor: Welcome aboard!
Varric: Delighted to meet you.