I've seen a couple of questions lately about putting Quakers and other birds together, or getting another bird. My personal experience is that Quakers are very apt to injure smaller birds, especially by biting toes, and should not be kept with them. Yes, there are certainly going to be a few exceptions, but most often this is true.

If you get a second bird, your Quaker's reaction will likely depend on how much it perceives that the new bird takes away from itself. If you don't keep them in the same room, and the second bird is primarily handled by another member of the family, it's unlikely that your Quaker will have any strong reaction, although it may "call" or imitate the other bird. If, however, your Quaker sees you playing with the other bird a lot, or if you have them out together, it's quite probable that the Quaker will get jealous and either get agressive towards the other bird, or aggressive towards you.

If your Quaker happens to LIKE the second bird, you may get lucky as we have with Bear and Beaker and have two loving pet birds that also are buddies to each other, or you may end up with two birds that bond to each other and become not so friendly to you. Each bird having its own cage and the two being allowed to be together for limited amounts of time, part of which you are interacting with one or both of them, is most likely to yield good results.