She.

She is one of her own kind. She'll give you the last bite of her favourite chocolate if you stare at it. She'll stay up late to open the door for you. She gets to dress up last because fixing your mascara or tie is more important. You achieved something you've been working hard for - an A grade, a small job or even learning to bake a cake; you think it's pretty personal and insignificant to others? Well, she'll prove you wrong by celebrating that ounce of happiness. She'll smile at the old couple in the park. She'll know how you'll react to what. Remember your photo at a party in which you look amazing? Well, it was her birthday party, and she took it for you. She's a giver. Your look alone will tell her exactly what you mean. She sees others in the mirror before she notices herself. She'll carry the heavier bags. A stranger's best friend. She'll get up to turn off the lights while she knows you're pretending to be so tired. Forgot that someone's birthday? Don't worry, she's got your back. She is happy to be lost in the tiniest things you may never notice. She won't delete a good photo because she looks bad in it (She may crop it, though). Your fake smile will not fool her. The first one to leave her seat in the bus for the more deserving elder lady. She serves you food before herself regardless of who is hungrier, but you know it's not out of etiquette. She's likely to fight harder for you, than with you. Your problems are hers. She'll smile at one and all. She'll notice your tears before they form their shape. She's a breath of fresh air. Her absence will bother you more than her presence comforts you. Give her a flower you randomly plucked and see her eyes sparkle. Is it the same as when you got her that expensive bouquet? Her sticking around goes without saying, so not surprisingly you may have taken her for granted. So now you realise how many times she's forgiven you without an apology. Yes, she's one of her own kind.

By now, you may already have been reminded of someone. She may be your long lost high-school friend, your sister, your girlfriend, your co passenger in a 7 hour flight, your mom, your cousin studying abroad, your wife, your daughter or even your best friend. You also may not have met her yet, but one day you will because she's out there.
So if you already know her, share this/tag her and let her know, and although she's likely to tear up, you'll make her day.