My theory on Mike
and BOB (not to be mistaken with Mike
Nelson 'Snake' and Bobby Briggs)
is probably one of the most solid ones on anything in Twin Peaks.
I have spoken to quite a few people about it, and in the light that
I usually end up explaining the story indicates that not much has
been written about these two major characters; I hope that this may
shed light on some of the confusion. Those who are very familiar with
Twin Peaks (i.e. have read Laura Palmer's diary) will know BOB quite
well; making several 'appearances' as written words in her diary during
her own entries, the relationship she has with this unknown being
becomes quite apparent. The first hint that BOB may at times have
the ability to infiltrate her words alludes that he possess a spirit
form able to inhabit a person's mind. Yet as we find out through Laura's
stories, she encounters BOB on numerous occasions between the ages
of twelve and sixteen as a tangible being; whether he is truly the
being she sees is another story, but he can also take human form.
Another form which BOB takes the shape of is the Owl. The owl is yet
another vehicle BOB needs when he is in a certain frame of mind. My
elaboration on these three main points at a later point will fully
explain why and how these transitions takes place. But in order to
completely understand this, I will explain who BOB is, his past, and
how it relates to Mike.
Years ago, when Leland Palmer was a young boy, he used to live in
a house on Pearl Lakes, just outside Twin Peaks, with his parents.
In a later conversation with Sheriff
Harry S. Truman and Special Agent Dale Cooper, Leland describes
a man, under the name 'Robertson', who used to live in a nearby house.
The man had long hair, and used to flick lit matches at the young
Leland, chanting: "You want to play with fire, little boy? You want
to play with BOB?" Given the fact that Leland's age is over forty,
it would seem odd that the man he is describing, recognised by Leland
years later in a drawing made of BOB as described by Ronette Pulaski
(who was assaulted by him with Laura), would still look the same after
such a long time. This suggests to me that something happened to BOB
between the time Leland first saw him at Pearl Lakes, and now. Here
we turn to Philip Gerard.
Philip Gerard is a one-armed man who claims to be a shoe salesman,
wandering about the inhabitants of Twin Peaks, spreading his business
for no apparent reason. Superficially happy, our attention is immediately
drawn to his behaviour, from the onset of his sighting by Hawk
in the Twin Peaks hospital following Laura Palmer's death. Philip
Gerard is seen entering the morgue, and as Hawk follows him, he vanishes.
Shortly thereafter, Dale Cooper has a dream in which the same man
speaks, the scenes panning between the Man From Another Place in the
Black Lodge, to BOB pacing around, 
grinning.
The One-Armed Man chants: "In the darkness of future past/The Magician
longs to see/One chance out between two worlds/Fire Walk With Me.
We lived among the people. How do you say, convenience store? We lived
above it. I mean it like it is...and it sounds. I too have been touched
by the devilish one. A tattoo on the left shoulder. Ah, but when I
saw the face of God, I was changed. I took the entire arm off." This
is intercut with BOB speaking: "Catch you with my deathbag! You may
think I've gone insane, but I promise I will kill again." A link is
made between BOB and the One-Armed Man. The facade of Philip Gerard
soon changes when Dale Cooper, following advice from the Giant
("Without chemicals he points"), withholds the medication on which
he depends on for a strange reason. As his non-sedated mind now settles,
we see an immediate transition from Philip Gerard to one possessed
by another form, as his voice changes completely, as do his mannerisms
and words. He elaborates upon the words spoken in Dale Cooper's dream.
At this point, I will draw together all the details I have gathered,
not only here, but also from previous discussions. Keeping in mind
the history behind BOB and the One-Armed Man, their connection is
as follows: A couple of years after the young Leland Palmer met BOB,
BOB met Mike, and they presumably became close friends. BOB, bent
on killing sprees, worked with Mike, who led the rampages. As an indication
of their vow to darkness, both had the inscription, 'Fire Walk With
Me' tattooed on their left shoulders. Whether or not both were at
the time spirits sent by the Black Lodge, inhabiting foreign bodies
to fulfil their deeds, I am not yet sure of. I think there are two
main possibilities at this point, both of which tie in well with the
present characters in Twin Peaks; one the one hand, both could be
spirits as just described, from the Black Lodge, or, both could have
been alive, human beings who knew nothing of the Lodges yet had the
same inclinations. Either way, the story continues: At some point
during their deeds together, Mike 'saw the face of God', as mentioned
above, and turned against the previous inclinations of killing. Knowing
BOB was unstoppable, that he would never see goodness, Mike killed
BOB, and cut off his own left arm, removing the inscription and thereby
cutting off his vow. Unfortunately, BOB remained strong in spirit
form, retaining not only his dark inclinations, but possessing the
ability to carry them out by possessing those not strong enough to
keep him out. Mike, in the meantime, turned his life to the good,
assuming the name Philip Gerard, with an extreme character of gentility
and happiness, innocently selling shoes. However, he was not unaware
of BOB's presence in spirit form, and in order to keep him out, used
drugs to sustain strength and render himself impenetrable. In the
light of these events, it becomes apparent why Philip Gerard lurks
about Twin Peaks; he is BOB's alter, an attempt at BOB's conscience,
trying to hinder BOB's actions. This is notably seen in Fire Walk
With Me when Philip Gerard is running wildy through the woods
as the camera cuts to BOB dragging Laura Palmer and Ronette Pulaski
to the train car. Philip Gerard is accutely aware when BOB is present,
and especially when he is about to kill. When BOB undergoes transitions
between possessing someone, and leaving their body to take the form
of an owl, Philip Gerard becomes aware of nothing else but the air
around him, as if BOB's spirit was teasing him.
As I have explained, BOB either was alive and died, taking the form
of a spirit, or has always been a spirit. What is certain is that
in spirit form, he is closely linked to the Black Lodge. He is the
messenger, the technician, so to speak, acting out the deeds as deemed
by those inhabiting the Black Lodge. The desire of the Black Lodge
is to aquire the souls of the good; obviously not of the bad, since
by the proxy of being bad one is already linked to the Black Lodge.
This is why BOB is often seen in the Black Lodge, most notably after
Leland has killed Laura Palmer in Fire Walk With Me, as he
stands before the Man From Another Place and Mike, Leland hovering
next to him in the air like a weak balloon. BOB not only takes pleasure
in his 
deeds
but gloats at those he inhabits. This mockery is seen in the ongoing
battle between BOB and Laura Palmer in her diary entries, as his constant
insulting of her leads to her own adamant attack on him. Of course,
in Laura Palmer's case, since BOB failed to possess her, he possesses
Leland Palmer, the weak father whose weaknesses he has known since
he was a child, in order to kill her ( knoing she would sacrifice
herself for her father's sake). One thing crucial to know about BOB
is that he does not possess his host 24 hours day; at times, BOB leaves
the body and takes form of the owl; this forms the basis of the Giant's
warning to Special Agent Dale Cooper: "The owls are not what they
seem". Most often throughout the series, BOB takes the form of an
owl after a killing, in order to return to the Black Lodge for a reward,
or prior to visiting the Black Lodge and mingling with the others
:)
