1-2

You reconnect with a relative (cousin, uncle, lost sibling, etc.)

3-4

A previous romantic interest. Either your separated prior and reconnected later, or the relationship didn’t work and you remained as friends.

5-6

An old childhood friend, either that you’ve never lost contact with or one you bumped into and realized no time had really passed.

7-8

A co-worker, which could mean a tedious day job or a comrade you shared basic training with.

9-10

You owed this person a favor, or they owed you. Turns out you two both like the same things. The debt has long since been paid.

11-12

This person had known your family or mutual friends for years and you always considered him/her as a big brother / big sister. Alternatively, you’ve known this person through his/her family or mutual friends for years and you always considered him/her as a kid brother / kid sister.

13-14

It started as a teacher or mentor relationship, but after the classes were concluded, you two stayed in touch.

15-16

An old enemy, if you have one, and it makes sense. You two came to an understanding.

17-18

You two met through common interests or mutual friends. Consider it boring but it’s also common.

19-20

He or she was more like a foster-parent, or rather the closest one you had to one.