On MH I came across a very interesting (but wild (but interesting indeed)) teory: Now we learned that Menos level Hollows levels up on eating other Menoses of same level. And Grimm got pwned and realised he is never could be the King. Ichigo, on other hand, showed potencial to be one. So, maybe Grimm will propose Ichigo to devour him. And he agrees thus gaining upgrade needed to fight Upper-half Espada...
Seems pretty unreasonable to me, but is interesting to be shared.
<feels sowwy for his Engrish>
There is a sig. You just can't see it.