First of all, there are many different categories of kin. Here are just a couple: 

Otherkin: identifying strongly with something outside of humanity

Fictionkin: identifying strongly with a fictional character or species

Within these groups there are many sub-categories.

Otherkin can be extremely broad, and usually relates to various spheres from the animal kingdom, fantasy, theology, religion, abstract concepts and more. 

Some common otherkin types include wolves, cats, rabbits, aliens of various types, angels of various rank, demons, elves, figures from mythology, dragons, fae, etc. It’s also possible to feel a strong enough connection to concepts to be kin with them, e.g. space, stars, ghosts, or the void. 

Fun fact: Tolkien elves are one of the oldest kin communities out there!

Fictionkin is the same concept applied to fiction.

Feeling a strong bond with a fictional character is a fairly common experience, but if you find yourself willing to call yourself by their name, or use pictures of them to represent yourself, you might want to start thinking about how much you identify with them and how.

If you identify as them in any sense, you’re definitely kin to some degree.

A few spicy indicators that you may be kin with something are:

You can be fussy or embarrassed about pictures of them as if they were pictures of yourself

You feel happy or comfortable when other people use their name(s) to refer to you

You feel any kind of “that’s me!” response in relation to them (an example of casual kin)

You feel as if you may have been them in a past life (an example of serious kin)

Depending on the kintype, there can sometimes be physical dysphoria involving astral wings, claws, tail, ears, etc

Kin as an experience is what you make it; it can be as serious or as casual as you like. Some people take it very seriously, and some choose not to. Everyone’s comfort levels regarding kin and how they want to feel about it are very different. 

As a concept it’s very YMMV—Your Mileage May Vary. You get out the same amount of effort that you put in, and not everything has to be your cup of tea.

Kin as a concept can:

Help you explore potential past lives

Help you cope with irl issues, such as when you relate to something else’s experiences and they help you make sense of your own

Help you connect with other people with similar interests or experiences

It can just be for fun

There are a few things that it’s generally frowned upon to kin:

Any real, living or dead actual person (this is called factkin — just don’t)

Fictional personas of actual people 

And as a final parting note:

We may be kin, but we cannot physically transform or change shape in this life, and anyone who claims to be able to is bullshitting you

We’re not oppressed just because we’re kin

Don’t date people just because of a kintype. Even if you’re both reincarnations of former soulmates, you won’t be exactly the same, just get to know them first? Common sense here