While I ended up liking the Otto-friendship scene a lot, it was REALLY confusing and I could see it being "fake" at the end. After all, we see a scene where Garf threatens Otto to not tell anyone "or else ...", and then hard cut to next scene and Otto somehow knew EXACTLY where Subaru was kept (he only saw in which direction Subaru and Garf went, right?) and frees him. I REALLY hope Otto is being genuine here, I really do. But this anime loves to fuck over Subaru and I can easily imagine the scene of despair when it's revealed that Otto actually acted under Garf's order ... I don't want that, though ...
If I had to put it to numbers, I'd say:
70% Beako actually cares about Subaru
30% Beako reminisced about her troubled mother