I don't see Battler and Beatrice teaming up in the very near future, because in the end, no matter how good she might inherently be, she is (if we can trust her final words in Episode 4) still the one who is going to be responsible for Battlers death.
I think her final sentences can be regarded as rather true, because for the first time she did not say that she was able to kill him because she is a witch and has superpowers and yadda yadda yadda.
Of course it could be another trick, but she more or less admitted that she does not have to be the Golden Witch Beatrice, but she is something that exists outside the known boundaries of the game.
I still consider it possible that they do a turn on the whole 'on the island' wordplay, but it won't happen this episode...maybe next Episode.
But the hidden elevatour to a subterranean dungeon behind the portrait, from which a giggling elderly Beato emerges at night is still a hilarious thought.
