A carrie ("carries" = plural) is a small fairy-like creature with very human-like appearances. They're often about the size of a thumb, but their height differs, much like their whole appearance. To fully describe what a carrie might look like, we need to explain their purpose further.
First of all, carries cannot be found from our world. They live in a dimension separate from ours, but are still tightly connected with us humans. That's because the whole reason to their existence is to guard their human pair's (or guardee's, as they're called in their world) heart. Whenever a carrie is born, it's given a necklace with a heart-shaped stone. This stone is the heart of the newborn carrie's human pair and the carrie is to protect the stone with their life. The tougher the carrie, the stronger willed guardee.
Due to the strong bond between a carrie and it's guardee, the thoughts of the human pair often meddle with the carrie's appearances: meaning that the carrie often looks like what their guardee dreams of looking like. As for aging, carries age with their human pairs. The only difference is that unlike the humans, who age physically the more years they've lived, carries age physically when their guardees' mind matures. Therefore some of the carries might look child-like even with their human pairs being 60-years old.
It's possible for carries to even grow wings. This can happen when their guardee has found the thing they're good at (like writing, drawing, singing... you know, their special talent). Even though humans can be good with many things, carries can only grow one pair of wings. So they grow their wings when their human pair has found the thing they do the best.
Whenever the guardee of the carrie is struck with really powerful negative emotions, the carrie might see a vision of what's happening in the human world. During these visions the carrie loses the control over its body and may do things without itself knowing. And this is the sad thing about these little creatures: carries, those usually so peaceful, jolly and loving creatures tend to get violent when it's about their guardees. If a guardee in the human world, for example, hurts another guardee verbally, the same damage of the one who got insulted will be felt by their carrie as well – as physical pain caused by the carrie of the bully.
Seeing that carries cannot control the actions of their guardees, they cannot help losing the control of their bodies. Their sorrowful fate is to just try to deal with the pain and hang on, protect the heart they were given in their birth. Most of the carries practice martial arts in order to be able to protect themselves and their guardee's heart in case an attack should happen.
As the guardians of their human pairs hearts, carries are the ones to take care of their guardees' love business as well. When a guardee falls in love, the stone, the heart the carrie of the said human is responsible of, will become a magnet and will be attracted by the stone of the carrie of the guardee to whom the owner of the heart is in love with. If the love is returned and not just one-sided, the two carries will proceed to change their necklaces. The hearts can never be changed back – this meaning that even if the love between the two carries human pairs faded, the hearts would still be with their new carries. This is dangerous because when the heart is not with the carrie it was meant to be with, the guardee becomes more fragile and might get hurt more easily.
Carries die if the heart they carry is broken. This basically means that if they do their job well protecting the said jewel, they can live as long as their guardee. Sometimes shatters of the heart can remain even if broken and if those shatters are reattached to each other, the carrie may be revived. It's a rare happening, but possible.