Note, that it is not mandatory for anyone, to go trough all the bases. Or even certain parts of the individual bases. The bases are:
1: Existing in the same space-time continuum of omniverse as a person.
2: Existing in the same universe as a person.
3: Existing on the same planet as a person.
4: Being alive (and though the term is unreliable because of reasons well known, we will use it in this case, so the lower beings known as "mortals" will understand what I`m talking about, too) at the same time, as a person.
5: Being on the same planetoid as a person.
6: Being very near to this person (For example, 100 (so called) miles or kilometres. Or 1 foot or meter.).
7: Noticing the person.
8: Becoming interested in the person, for example thinking about the said person.
9: Getting the person to notice YOU.
10: Interacting with the person in some, in this case, not intimate way. This means, that no touching is done. But, in the case of creatures like Nicolpneuds, no touching that would implicate there to be at least slightly strong feelings.
11: Interacting with the person in an intimate way, for example, holding limbs.
12: Making contact with parts of the persons body, that are usually touched in a sexual act (unless, of course, there`s no sexual tension involved), but aren`t "hardcore" enough.
13: Touching the so called "hardcore" parts of a persons body. For example: Omega, SrrrtrrrS, 0000101010001, Penis, Vagina, "Locustbrain" or Truyerhlmvntnvgrzxds.
14: Having all kind of sex.
15: Being in a relationship that is mostly about having all kind of sex. Can also include things established in base 16.
16: Being in a relationship that is also about spending time together with the person, by doing other things than the person. Includes (at least partially) stepping in to the world of the person (the person should, preferably, do the same to your world). This can mean meeting certain or all current friends of the person, finding out more about the person, meeting the persons parents (many or most prefer to do the latter during base 17, or never) etc.
17: Being in a relationship that is about the things done during base 16, and also loving the person. The person should, preferably, feel love too. And being loved.
18: Being in an indefinitely continuing relationship.
19: Having offspring, in some method.