Ok, I have some things to say, the first is this:

Spoiler!

Was I the only one that was like ?:
- oh, Aizen has a Quincy-Shinigami hybrid son (theoretically better than just Human-Shinigami hybrid) ,
- or, Aizen did it again, he pulled another Clark Kent on SS .

The second thing:

Spoiler!

Isn't it contradicting with his "caring" look that he gave them (at the first page) ?

I'm not sure, but it's possible that the girls will die and then Allon will morph in to an Arrancar (as he is currently a hollow(?) since he has his full mask)... on the other hand, I'm not sure if he can be called a hollow anyway, especially since he doesn't seem to have a hole.