I don't have a problem with the companions origins. But I have no connection to the PC, he is a mercenary. Right now you could play the game without your self made main character (3 person party) and would miss nothing at all. Every encounter and every story bit would be the same. Why should the rest even team up with him? What are his goals? ( ... yes yes get right of the brainbug ... this feels like lazy writing).

The companions are trying to overshadow the main character at every interaction (as it is no difference if you or them do the encounter). In divinity it was fine, because every companion was in fact trying to overshadow you or at leased the divinity, who touched them was.

I would like to see a short playable origin story in the beginning to connect with the main character: Start with an origin story like in DA:O (not even as long) for each companion and one for self made characters (something more generic like BG I: for example a orphanage. Candlekeep in the beginning was CHARNAME's origin story)
Give a self made main character a unique quest line. Let the characters in the world react stronger to his reputation, race, class (and unique origion story).

Furthermore give the main character (no matter if it is a origin character or self mad) something special... being a spawn of a god had a nice touch in BG laugh .. and involve him in a special way in the main plot eg give him something which no of the companion can do.

Add non origin companion for a more natural party development in later parts of the story. It's enough to give them some banter and a quest line. You could even make them temporary.