Relationship Level

 Every companion in the game has a Relationship Level related to Rook, and the choices you make (and not even specifically about the companion, but in the world in general), what you say to companions, how you help or don't help them, and more all play into it. Every time you rank up a companion's Relationship Level, you unlock a skill point to spend specifically on that companion. Though companion skill trees pale in comparison to Rook's expansive tree, which features passive abilities, combat abilities, and more, as well as paths to three unique class specializations, there's still some customization here. 

Each companion has access to five abilities, but you can only take three into combat. Thus, it's important to strategize which abilities to spend a skill point on and how those abilities can synergize with your current build on the battlefield. Though I couldn't confirm, Dragon Age series art director Matt Rhodes hints that companion issues, problems, and personal quests will play into this Relationship Level and how a companion interacts with Rook. 

"Bellara Lutara, for example] has her own story arc that runs parallel to and informs the story path you're on," Rhodes tells me while I watch game director Corinne Busche play through a linear, story-driven mission in Arlathan Forest where Rook is searching for Bellara. Busche adds that "relationships are key, not only romance but friendships. We wanted to lean into not just the relationships the characters have with you but the relationships they have with each other. It's a found family, and at the end of the day, they need to trust they all have each other's back."