Numbers.
If there is 1, then 2 is obvious, and 4 and so on and so forth by God.
But if there is 1, then there is also half, and 1 and a half, and 2 and a half or 3 even, which is 1 and a half plus 1.5, its mate, you get the idea.
Don't forget the negative values as in temperature indicators for example, as in -1, -2, -3, etc.
Every thing one can think of has a pair somehow somewhere.
Only God Remains The One Truly Unequalled, Incomparable.
For example, my tablet can serve as a table of sorts somehow with four corners as four legs. It can even serve as a football pitch with 22 soccer players one can only imagine, which only God Can Make Real any time, since He Allows your imagination to come up with creative ideas to begin with, though to each their specialities.
If you can't find a pair for something, then you are already a pair for it since you are thinking it.