Like pets, I think we should have the option to place companions in our house. Hear me out on this:
Companions that you place in your house will roam freely around that specific area, like pets. If you leave, then they will simply leave your inventory, but when you go into battle, selected ones will appear once again to help. In order to have a firstmate, you must keep it in your inventory so it may trail you around on your travels.
I also feel the same on Ships. What crew doesn't appear walking around on a ship? Depending on the ship's size, a number of crew members can walk freely on your ship, possibly giving you warnings of nearby enemies or helping with cannons.
I feel this will add a more realistic and exciting aspect to that of your crew! Feel free to add on to this idea, if anyone would like.
I agree it would be really nice if the companions could help you on the ship. I think they should do that and we pick there jobs. There should be Cleaning, tokens, look out, and some more but it should have at least that.
It would also be nice to have the companions at the house for decorations and you can have them talk to you and other people.
I don't have anything else but I ill say it would make it super fun if that could happen even if it's just some of it.