I really love this interpretation of Bern’s behaviour. I’m happy people like this exist, because whenever I read posts about her, most of the people bash her for literally every misfortune in Umineko.
It’s sad to see that more people would rather excuse (for example) Kyrie’s actions than Bern’s (even though there are much less clues regarding theories about Kyrie not being so bad).
Personally, I am currently a supporter of ‘Tohya’s avatar’ theory, and I suppose there are sufficient clues for it [At least for Bern not being that bad…Examples? Well, they were there since EP6 — the first being the fact that Bern knew Beato would come (“I bet she comes miraculously”) that Battler’s logic error could be solved, the second is the meat on the plate changing into a plate of biscuits and, at the end, back into meat in ??? — of course, that could be interpreted other way than I do — and Bern’s disgust at the task Featherine gave her, and of course ‘fellow monsters’. Then we’ve got the very nature of EP7 — hiring a competent detective (known from his focus on motive and ‘heart’!), going through all the trobule of finding Lion from one Fragment of 2,578,917, even introducing Lion, and giving an avatar so that Sayo ‘wouldn’t have to expose the pitiful form’, and, of course, a very tactful treatment of difficult issues of Sayo and giving her opportunity to confess her sins.
During the EP7 Tea Party, when Lion asked the reason for the reason for doing what Bern did, she said it was because ‘she wanted to get back at her’. Then, she said she would send Lion to the moment just before Kyrie’s murder and she’ll make Beato watch that. Honestly, I find it odd. After all, Clair (Beatrice) was already long dead at that point. Isn’t doing all of this for getting back at someone, who can’t even witness the revenge, a bit of overkill, even for Bern?
When we add Will’s comeback, everything becomes even more fishy. Also, at the end of EP7, he said ‘I thought decent witches didn’t exist, but I might have to change that theory’, and in TP — “There was no way you’d end things on a happy note.” While this may not be an argument in itself, if we combine this with the fact that Will’s actually a Bern’s piece and Bern has the ability to close off any part of a Fragment she desires (she showed it at the beginning of EP7) it seems…strange, doesn’t it?
Why would she do something like that to Lion, though? If we consider that Lion, as Will stated, was the main character of the episode and the fact that it was never specified in red that Lion died there (especially that the Fragment is suddenly cut off), AND what Bern told at the end (“collect dust, unable even to die, and disappear”, and then “Come kitties, I won’t tell you to kill them” — I think that was Bern’s way of refusing to tell the viewers what happened later to Lion after Kyrie pulled the trigger)… I think I may have a certain theory about that.
And there’s of course whole Ange’s arc (EP8). There is a good quote I’ve recently spotted — “I promise to release Ange after the game ends. I swear it on our relationship” (sth along these lines) – Bern to Lambda — and then — “My game is far from over” (or sth like that). There’s the thing about Lambda seeing the script — if Bern is Featherine’s “Reader”, and she also is a Voyager, I don’t think it is a big stretch to say that there’s a big possibility that Bern also saw it. And, of course, the thing at the end — both Battler and Ange ‘dying’, and of course the way the things end in ‘???’.
And, obviously, the well-known quote 'It was fun being an antagonist"…wait, wasn’t she claimed to be a sore loser? Or maybe, she has achieved her goal? Combining all of the above facts(or clues?) with all the things people said earlier in this topic about Bern-chan’s backstory…feel free to make your own conclusions 
] (Sorry for disorderliness, I’m in a hurry)
These things might all be my presumptions… However, I think I just can’t bring myself to hate Bern :> Still, I can understand why people don’t like her.
Even Ryukishi himself said in an interview that our view of Bern can change drastically, depending on whether we have love for her or not. I hope her character will be expanded upon in the next WTC series (she is supposed to appear, isn’t she?) and she won’t be playing the villain next time, as Lambda said it :>
“Without love, it cannot be seen.”
