Maybe you could have a small little form for people to fill out to go with their initial tag that tells a bit about their character.

Like maybe a simple name, canon, a blurb about the character, and then a blurb of what types of characters they may be attracted to.

For instance, my character is not very trusting or sociable. He'd definitely not go well with someone like himself, but would be more drawn to someone who is his opposite.