Thing is, we don't even know if all the Unknowns are even on the same side. I think we can safely assume that the blonde kid with two keyblades (Oblivion and Oathkeeper chains) and the blonde-haired Unknown with the two keyblades (same ones as before) from Another Side, Another Story/Deep Dive are the same person.

In one trailer it shows the kid (not in Unknown cloak) fighting Axel. One of them says something to the effect of, "I won't let you get to Sora!" Either way, one of them is looking for Sora. The most likely options are that either Axel is looking for Sora and the blonde kid is protecting Sora, or that the blonde kid is looking for Sora and Axel doesn't want him to find Sora.