Being an "axis" in terms of anti-US actions stretching them to the brink of collapse from all sides or jointly blunting their sanctions potency altogether is enough for this conversation. Kicking their ass in general basically. After the US is gone, so will this temporary linear "axis" go.
They don't need to marry each other's citizens. An axis simply means an alliance or agreement of some sort, and there is clearly such a thing specifically regarding moving against the US-led block, diplomatically, economically, and militarily to an extent that is necessary over time.
Everyone helped Russia in this war to an extent, and Russia was winning, outproducing the entire West combined, so they clearly didn't need more. Just like China alone also is capable of doing the same, but this time even in a more direct confrontation as they are the main target.