Why did Frank lure Donnie away in the first place? This has fucked with me for a long time (well for a month). Thanks to this site:
www.tonystuff.co.uk/darko-spoilers.htm#top, I've managed to almost grasp it. I say almost because there are still things I don't get.
The jet engine comes from another universe's future. When it crashes through to Donnie's 'primary universe' a Tangent Universe is created.
The jet engine is 'an artifact' from ''the future'; it caused the Tangent Universe when it crashed in to Donnie's bedroom. Tangent Universe's are bad. The world can only sustain one for 28 days, and then it (the world) will be destroyed.
Now: this is where the confusion for many (including myself) arises. Why did Frank lure Donnie away in the first place? Why not let Donnie die and then be done with it.
Well: the only way to destroy the Tangent Universe is to send the artifact back through. It must be sent back through the worm hole (or whatever you want to call it). Donnie dieing is not enough: it must be sent back through; only Donnie can do this as he is the closest to the artifact when this happens. He becomes the Life Receiver because he is closest (by total fluke and with no 'pre-destined chosen one' mumbo-jumbo) to the artifact. If Donnie were to die at the get-go, he would not be able to send the artifact back through.
Frank comes from the future of the Tangent Universe (in which he is killed by Donnie) to guide Donnie through to events (Frank, Gretchen, mum and sister being killed) that leave Donnie no choice but to then go back in time. What motivates Donnie to go back in time is to save his loved ones; saving the universe is a bonus.
The journey that Donnie goes through, that Frank guides him through, is to meant to show him things that will motivate Donnie to go back in time. Good things and bad things happen that do this:
Good things:
1. Donnie learns that he is not alone (the love of Gretchen, the love of his mother, love from Cherita). He then is not afraid of death.
2. He is not crazy (his therapist tells him his pills are fake)
Bad things:
1. Gretchen dies.
2. He kills Frank.
3. Mother and Sister die in plane.
By going back in time to the Primary Universe, to before when the Tangent Universe was created, and staying in the bed and getting killed by the jet engine which WHICH IS COMING FROM THE TANGENT UNIVERSE HE JUST CAME BACK IN TIME FROM, he closes the "loop''. He went through the Tangent Universe and set in motion the events leading up to the jet engine falling through his room; but, this time he stayed in his bed and got killed, ending the Tangent Universe. At the beginning of the movie, the first time the engine comes through: that engine was the engine coming from the Tangent Universe. Donnie sent the artifact (and himself) back to October 1st.
This of course begs the question again: why did Frank lure Donnie away? He did so because the Tangent Universe is not the Primary Universe. It is not reality. It is an alternate reality; however, it has now become the only reality. So, the Tangent Universe was created by an artifact from the Tangent Universe! Think of time as a loop, and not linear (although the site from where I got most of this says not to). The Tangent Universe is the 'new reality' and needs to be destroyed in order for the Primary Universe to survive. Frank lures Donnie away because the only way for the Tangent Universe to be destroyed is to send the artifact back through the hole, thus sealing (somehow) the wormhole from which it (the artifact) came through.
If Donnie had been allowed to die at the moment of the Tangent Universe, he would not have been able to (now hold on) go through the Tangent Universe, set in motion the events that led up to the jet engine falling off the jet, sending it and himself back to the Primary Universe, and this time deciding (cause he has the power) to die: thus altering reality; destroying the TU. Another person on this site said to think of it as a zipper: the artifact going through first is opening the zipper (TU); the artifact going back in time and through the wormhole again is closing the zipper (PU).
[glow=red,2,300]Now how about this: The jet engine at the beginning is sent back in time from the future from Donnie himself![/glow]
October 1 - Initially Primary Universe
Jet Engine Crashes from TU future.
TU Created
Frank saves Donnie so he can go through TU and set in motion events that will lead to jet engine crashing
October 2-28
Movie happens
October 28
Donnie sends engine back in time to moment it crashed through in to Primary Universe - October 1
Donnie himself goes back in time.
October 1 - Back to Primary Universe
Donnie stays in bed; gets killed.
This destroys the Tangent Universe.
It destroys the TU timeline; the TU reality.
There are of course still - pardon the pun - 'holes' with this theory. Thinking of time as a 'loop'' for instance necessarily need not apply here. Time can be seen as linear while at the same time thinking of 'past' and 'future'. When 'fate' is brought in to the discussion, then a 'time loop' has more validity, as you can not escape fate: what is meant to happen to you will happen to you no matter what you do.
But Donnie is not necessarily 'looping'. He is going back and forth in time. Frank is coming from the 'future' and showing Donnie what happens. The artifact and Donnie don't 'loop' when they go back in time, they are travelling back (it can be argued) on a linear time path. HOWEVER: in a sense a 'time loop' is occurring because
Donnie sent the jet engine (which we see in the beginning of the film) himself!
If you think of time as in a 'loop', Frank luring Donnie away doesn't make sense. If you think of time as Linear, then it does; for then 'time' only happens 'once' and (if you believe in time travel) can be altered. If you believe in 'fate', then if it were to be Donnie's fate to die, then Frank luring him away doesn't make sense. Unless you think that the whole 'linear time' belief is controlled by 'fate'. the jet engine was destined to fall through; Donnie was destined to go through the TU; Donnie was destined to go back in time and die by being crushed by a jet engine he himself sent back in time to kill him -- a jet engine from the future that was sent back in time by his future self.
So. There you are. Still confused, eh? I still am. I've managed though to make sense of it a little more. Please feel free to comment, edit, correct. I'm going to bed now.