I would not recommend catching one or adopting one, even though I would love to! They don't tolerate humans. Don't even try they are way to clever, as are the real 'faries' anyway.
You should just leave them alone but also if you really want a fairy so bad first you must find one. The most important thing to keep in mind while searching for fairies is to believe that they are there to find opening yourself to other world possibilities.
Any natural setting is home to fairies. Really doesn't matter if it's a roof top garden, or vast woodlands, but there must be Nature's hand at work. Forest, streams, ponds, beaches (dunes are great!), snow banks, waterfalls, birds' nest, well you get the picture.
You can find fairies in a field at midday, by a stream or river, near trees and bushes, in a wood or at the bottom of your garden. If you can't find them there, look on flowers because fairies love them!
Or, build a fairy home, put things that are shiny - put grass and dirt in front and on the house. Leave a tiny drop of water! Put what you think a fairy would like! Get creative just build a miniature house. Fill acorn tops with nuts, berries, and seeds.
Alternatively, look for a ring of mushrooms. Fairies love to dance in them. Then build a net out of a spider wed and a stick. When the fairy sits down on the mushroom she/he will be caught.
Oh yeah! Give them some gold. You have to find a rainbow. Then go to the end closest to you and follow the rainbow. It's best if you constantly watch the rainbow because they don't like to stay; and leprechauns control the rainbow because leprechauns hate to lose their gold.
You cannot exactly adopt a fairy. Truthfully, I think it is mean trying to catch a fairy for your own amusement, but once you catch them, they can't disappear... as long as you take their wands away.
You can, however, become FRIENDS with a fairy. Being friends with a fairy means you'll see a fairy. Being friends with a fairy means you'll start seeing the BEAUTY of nature. To become friends, speak aloud at a nearby neighborhood garden, or if you have one, then one at your house! The garden must be outside, and it must be at least three yards wide. You must talk aloud for ten minutes at the least every single day. Talk aloud to them at least five times a day. Soon, you'll really start earning their trust.
And finally, say this chant:
Fairies fairies, sit upon my knee,
I'm as kind as ever can be.
I am not SELFISH nor HARMFUL!
Repeat the chant above. You can only HOPE...