Ah, the flashback. It's a device used very commonly used and one frequently derided. At the root of the flashback is the humanist/liberal assumption that the roots of a person's character and/or present circumstances lie in the past, and therefore through viewing their backstory we can come to understand them. Lost went so far as to include a B- or C-plot in every episode constructed entirely of flashbacks, with the assumption that this would help us to know the characters involved.
There are, however, a lot of good reasons to doubt the way this device is deployed. In addition to the idea that revealing a character's past by just displaying it is easy and perhaps lazy, the concept that learning a character's past necessarily sheds more light on them is kind of an ideological construction as well – see IOZ and Mark Fenzel on this topic.
Flashbacks are also a big part of Mawaru Penguindrum and are even marked off by their own signature device, the blinking subway sign. They are even diegetically (at least in gg's translation) described as flashbacks.
But the flashbacks we see in “This is What Drives Me”, that even begin the episode, don't quite fit into the Lost archetype. These episodes simply illustrate what we already knew – Kanba is loyal to Himari and desperately wants to protect her, and that at one point the siblings had parents. This raises the question – why include this event at all? Is it just lazy writing, or is there something deeper going on here? 
The idea of fate or predestination has been presented as central to Mawaru Penguindrum, evident from the opening of episode 1. The repeated subway motif seems to depict an essentially linear and restricted plot structure. During the eyecatch the train moves from one stop to the next, as the plot moves from one episode to the next. There's no doubling back or going off in an unexpected direction – fate has one path for you, and it's not a path you can deviate from at all. By contrast, the central motif of Kunihiko Ikuhara's previous series Revolutionary Girl Utena is the spiralling staircase that Utena climbs to every battle. The show is structured like that staircase – it progresses, but in a way that brings it back around in circles a lot.
So under the Penguindrum subway model the flashback, in which Kanba and his father help a sick Himari through a typhoon, is just an early stop on the line. We may have “got on” after this stop, but that doesn't stop it from being the inevitable predecessor of where we are right now. There isn't the humanist point of “this is what made Kanba who he is”, which has the corollary of “if this hadn't happened then Kanba would be different”. Under this model there is no if, this could never not have happened and Kanba could never be different. This is the deterministic model of time, and it's a somewhat bleak one. The episode is entitled “This is What Drives Me” -- on the surface a normal bit of modern self-help-book-talk but structured as a disturbingly passive sentence. The characters are like the train – driven by an external force, not their own will. Even in the explicit plot Shouma and Kanba are simply forced into following the hat's orders instead of having their own free choice -- if this were a RPG campaign the proper term would be "railroading".
In this episode, however, the train model starts to break down. For the first part of the episode, the plot is a mechanistic extension of what we've seen before. After the flashback opening we begin in the hospital, where Himari is undergoing follow-up examinations after her miraculous recovery. This is a natural progression from what's previously happened, an almost beauraucratic next stop on the line. We also see Natsume discussing things mysteriously with Asami, who appears to be her minion. These two are in a different type of plot, the mysterious-people-talk-mysteriously puzzle plot (see my Kamisama Dolls review), but one that also adheres to a pretty linear structure of inductive reasoning. The promise (one that may or may not be fulfilled) is that as the series continues this plotline will slowly progress by having more and more information revealed until the big final reveal, presumably towards the end of the series.
So far, so straightforward. The first half of “This is What Drives Me” consists of exploring the past of these characters, through the arrival of the older generation that they have a tenuous relationship with. Ringo's lunch with her father and Kanba's meeting with his uncle are both examples of this, and are directly juxtaposed. In one way this is simply more of the backstory-revealing that the flashbacks started. We're learning where these people came from, the part of the linear journey that we didn't get to see. But there's also a friction between past and present. Ringo fears that she's being replaced in her father's life, and Kanba's uncle wants him to sell the family house and risk splitting up the three siblings. Suddenly the past is not just a set-in-stone part of the linear story: it's actively in danger, possible of being erased and twisted. Of course, what's at stake is not the actual past but the objects that represent it. Still, it's a bit of a challenge to the linear progression the narrative has followed up until now.
(I also love Ringo's distress over her father's phone charm. Mawaru Penguindrum has been using Ringo to satirize the cute craze that has swept anime in the past decade and all its materialistic trappings, from her homemade bento boxes last episode to the cell phone charm which is apparently as significant as a royal banner in proclaiming alleigance.
There's a lot to love about this shot – the framing device of the cell phone camera, the zoom-in function that looks at first to be extradiegetic, and the interesting idea that Ringo can only see the ugly truth when it's mediated by technology. Her reaction to discovering that her father is no longer using their signature cell phone strap is also telling: she immediately starts thinking about her imaginary storybook romance with Tabuki, retreating back into fantasy.)
The dinner scene is, however, where things really start going off the rails. (I know I'm dragging this train metaphor out, but bear with me.) Shouma tries to convince Ringo to let him see her notebook, and through his insistence they both end up revealing their secrets to each other. The covert stalking plotline has been ended in a surprisingly nonviolent way – both characters learn what's happened without any sudden discovery or climactic fight. All it takes is two people who can't keep their mouths shut, and we are far away from our presumed destination.
Then Himari enters her penguin-head mode, and things get really crazy. We have the same introductory sequence as the previous three times, but still something is different – namely the presence of Ringo instead of Kanba. Penguin-Himari tries to go about things as normal, lecutring her captured peons and eventually dumping one into a pit. But she isn't aware that the internal logic of these sequences has already been broken by the presence of Ringo. When Ringo pulls herself up out of the pit, we know that the order this show has spent the past four episodes developing has been completely disrupted.
Ringo is the X-factor -- she doesn't know the rules of this sequence, as can be seen by her shock at Himari's sudden foul-mouthed cruelty. This is contrasted with the resigned head-shaking of Shouma. At first we think that Shouma is the wise on in this situation, knowing what's going on, but it's precisely Ringo's ignorance that lets her do what Shouma has never even tried to do and break the exact script (definitely a kind of fate) of this sequence. She runs up the stairs, violating the linear and almost class-like structure of this strange space where Himari always descends but the brothers can never ascend, and then whips off the penguin hat and throws it away.
This is the first time we've seen the snap from this fantastical sequence back into the real world, which is sudden and abrupt, and marked by a shift from symbolic consequences (the violation of the normal sequence) to real ones (Himari's collapse in the absence of the hat.) We end up with a great sequence of Kanba chasing the hat through a stormy city that has a kind of Chuck Jones-esque humour while also creating serious suspense as to Himari's fate. Moreover, the chase directly paralells the earlier flashbacks, with Kanba braving a terrible storm for the sake of his sister's health. Ringo's intervention has disrupted the linear sequence of the story, causing it to loop back on itself, the past repeating.
Both events -- the flashback and the present-day chase -- are structured in a similar way. Kanba goes after Himari, while something stops Shouma from doing the same. He gets hit by something midway through, but is rescued by intervention of another (first his father and then his penguin). In both cases, we never see him actually achieving his goal, only the aftermath. This is one of the major ways Ikuhara uses repetition -- after seeing something repeated so many times, a difference (minor or significant) is always meaningful.
ANN doesn't list episodic writer credits for Mawaru Penguindrum, but just has Ikuhara and Takayo Ikami as writers for the whole series. If this is actually the case, then it makes sense -- with such a thematically intricate and firmly serialized story, having a strong singular creative presence creates the necessary cohesion. However, Ikuhara is listed as doing the storyboard here, which suggests an extra degree of attention paid to what I beleive is a pivotal episode. The episode is directed by Koichiro Sohtome, who seems to be a relative newcomer, and he mostly follows in the footsteps of previous episodes. He continues the stylistic devices of previous episodes, but doesn't really bring anything new, even when that might have been useful -- some more shot-by-shot paralells between the two storm sequences, for example.
There's an image in this episode that's been getting a lot of attention from bloggers lately. During the dinner conversation we see one Shouma's penguin spraying down some roaches, as we've seen the critters do in a previous episode. However, instead of getting rid of the roaches, this causes a whole bunch more of them to descend on him, and the penguin is quickly overwhelmed.
This has been interpreted as signifying Shouma's fecklessness in the conversation, as well as the rottenness hidden in the cute Takakura house. But I think it also reflects the breakdown in linear logic. Eliminating bugs is, at least our erstwhile penguin assumes, a linear task -- you eliminate one, there's one less, and if you do this enough they'll eventually be none. But here eliminating one creates a whole bunch more. Straightforward logic no longer applies.
It took most of the series to reach this point in Utena, where the logic we'd been learning for most of the series broke down and left our heroes stranded. In Mawaru Penguindrum it seems to be happening very early, which should make for some very interesting developments in the weeks ahead.
 There's an intruiging theory that all of the main characters in Mawaru Penguindrum are actually dead and in some kind of purgatory where they have to repeat their lives until they find peace. I don't really want to go into plot speculation in this blog, but it's put forward pretty clearly by a day without me. If this theory turns out to be correct than the flashbacks have an obvious purpose, subtly showing the point where Kanba (maybe) died, but I think there are more interesting explanations here.
Next Week: Another wildcard entry. We'll have fun fun fun until our daddy takes our T-Birds away.