The story line shifts and changes as the main character goes on different quests and meets different characters, some of whom can be come his companion. Now companions enhance the main characters abilities to do a lot of things: some companions make it easier to find food, some to pick locks, and others may help with your fighting abilities. Believe it or not, you can even romance some of them. Mass Effect 3 was the first game in which there was same sex romance, how about that.
Anyway, I don't play games the way writers write them, sequentially. I move around the map in a very nonconformist way. As a result I didn't get to the Cambridge Police Station until rather late in the game, which means I didn't meet up with Paladin Danse until recently, and it turns out he's a good companion. He even dresses up well.
And, unfortunately, I'm now involved in a quest in which his survival is at stake, and even though I make the game as individual as I can, I'm still forced to follow the path the writers laid out. So now I'm Dansing through my few remaining choices just to keep him alive. I may just have to dump my last 4 hours of game play in order to get to his personal quest sooner.