The whole question from Quora was as follows:
My parakeet isn’t really active (eating, exploring, playing) until my sister’s parakeet comes around. That does this mean?
Birds of a feather flock together and you don’t have any feathers.
It sounds like your parakeet prefers the company of another parakeet and is happy when one comes by.
Ideally, when we bring home a baby bird we hope and expect that it will bond with us and become a great little birdie buddy.
It doesn’t always happen for many reasons. Some obvious some not so obvious.
Budgies are flock birds, they want and need to be with other birds or creatures that can take the place of other birds.
Like a human, or a dog even.
If you brought home a single baby bird, it would likely become close to you if you spend the time with it needed to allow it to become comfortable and eventually look forward to seeing you.
This would be a daily bonding plan, spending a little time with the bird several times during the day.
If the bird does not get this type of attention from you it will seek out companion or comfort in other ways.
Windy City Parrot’s Budgie Aviary ~ video
This can be in a mirror, which can replicate the missing buddy, even shiny bells can serve this need for companionship.
If your parakeet was with other parakeets early in its development and did not get bonding attention from you, it will always prefer to be with other parakeets and get excited to see them over you.
This is a natural behavior. You may wish to get another parakeet to keep your parakeet company and simply enjoy watching and tending to their needs while they live together happily.
A few years ago we took in a feral parakeet (a wild one) and saw it was scared and unhappy alone, that it could not be tamed considering its life outside, so we found it a buddy, and then even another couple to be there.
The feral bird calmed down and still lives happily now with 9 others in a large cage. They can’t be handled but they are happy and so much fun to watch play.