Pacific Parrotlets
I have three pairs of parrotlets that produce green, blue and split to blue babies.  My parrotlet babies are removed form the nest box for hand-feeding at about 10 days old. This gives the babies a really good start on life and also helps increase the odds of them being good pets. 
They are easy to keep happy and easy to take care of.  Their personalities vary widely.  They do not bond to thier hand-feeder, so I usually get to see the worst part of their personalities.  Most settle down and make great little companions once in their new homes.  But there are a few of the little devils that insist on being nippy little dragons.
Most make decent companions for teenagers and adults, but they are too full of attitude for little kids.  Anyone with little kids in the house will need to watch them very carefully around parrotlets.  My experience has been that little kids want to hold them, the little bird might not want to be held, and the kid squeezes them to make them hold still.  They are NOT good pets for little kids. 
Overall, if provided with a nice sized cage, and plenty of toys to swing from, they are very content little birds.  They make the most adorable little chirping and chortling sounds that are pleasant to most people's ears.  Most of them love to come out and play with their owners.  However, many of them have very busy beaks and will try to chew on your cloths or neck.  I recommend draping your shoulder with an old washcloth to give them something interesting to do up there, or just not allowing them on the shoulder to start with.
If you want the baby to stay friendly, your best bet is to keep it as a single pet.  Pairs of these birds are adorable to watch, but they tend to not like people a whole lot.  Parrotlets are one of my favorite species to just sit back and watch.  They love toys with little pieces and lots of motion to swing from.  While they love to interact with their owners, they get along just fine if you suddenly have to work more for a few days or go on vacation.  They do tend to be very accident prone, so be very careful about what toys you put in the cage, and never leave them unatended outside of the cage.  They have been known to crawl into full glasses of water and drown or get eaten by other pets.  With good care they should live to be 12+ years old.

Most parrotlets do well with a very light touch.  They tend to object strongly to being forced to sit still and be petted.  Owners that become disapointed because the bird won't submit to petting, often accidently teach the baby to bite by cupping it in their hands and petting it against its will.  A better method of interacting is to hold the bird very loosely, so that it can crawl freely from hand to hand.  This prevents the baby from feeling like it needs to bite in order to make its wishes known.  Once the baby knows that it won't be forced, it is usually more willing to accept other kinds of handling.