So this was just a bored thought that popped in my tadpole infested brain and I thought why not share it?
Since Gale stated that he has a cat I wondered what all the current companions would say if they had their own pets? And through thought I came to the conclusion of:
Gale: cat (I feel like it's a calico breed)
Wyll: a husky (or some form of big dog)
Astarion: rat boy gets a rat
Shadowheart: a snake maybe?
Laezel: either a dragon or a turtle.
Feel free to let me know about your own conclusions
Or even let me know what your main characters pet is too!