Divinity Original Sin 1 let you keep all four companions with you. On my first playthrough, I took Madora and Jahan, and left Wolgraff and Bairdotr to the side, and yet I still completed notable parts of Wolgraff's quest, especially the conclusion even though he hadn't been with me, and I missed out on all his interactions. It felt kinda unsatisfying because I missed out on all the interactions.
DOS1 has two main characters and up to two companions at one time. Companions worked more like in most other RPGs in that you couldn’t do things like initiate dialogue with NPCs whilst controlling them, but you could swap them out.
In DOS2 your companions are just as important as you are, you can initiate dialogue while controlling them, but you can’t swap them out for others. There’s basically 4 main characters, although only one of them is really you.
DOS1 supports 2 player multiplayer and DOS2 supports 4 player multiplayer. Coincidence? Probably not.
