One of the things for which I'm infamous is the advocation of the following:
Yui : Rei :: Dr. Katsuragi : Kaworu
The basic idea gets far more rolling eyes than it deserves, in my opinion, since, at a barebones level, it rather intuitively satisfies a gap where numerous preestablished patterns of correlations converge. (See e.g. here.) The problem is that, as with so much else in NGE, there is no way to empirically prove it OR deny it, only weigh its probability.
I've noticed a handful of items in the show that may be, rather subtly, suggesting ties between Kaworu and the three members of one particular "character family": Misato, Dr. Katsuragi, and Kaji. Here I'll attempt to present observations of possible relevance, while posing questions and making suggestions along the way.
RULE: I'll be happy to get this over with. You can help me out by not interjecting with your doubts, or whatever, until at least all of Exhibit A is up. You'll know when the green light goes on.
*****
EXHIBIT A: Misato & Kaworu
In episode #24, Misato takes an acute interest in "that boy" early on, her suspicions piqued before she even sees him in the flesh. Just to set the stage, I'll start things off with some generic copypasta.
After Asuka is recovered, Misato thinks to herself...
Misato (MONO):
And today, Asuka's replacement, the Fifth Child, arrives.
Everything is just too perfect.
Later, she and Hyuga-kun discuss intelligence on the car train.
HYUGA (OFF):
It appears the Fifth Child has just arrived.
Misato:
Kaworu Nagisa, his past records have already been erased.
The same as Rei...
HYUGA:
But the one thing we do know is
that his birthday coincides with the Second Impact.
Misato:
The Committee sent him directly to us.
There's bound to be something to this.
HYUGA:
In the Marduk Report, the matter of the Fifth Child
is also designated as confidential.
So, I did a little hacking into the Intelligence Department's database.
Misato:
You're so reckless!
HYUGA:
It was worth it though.
I found out where Miss Ritsuko's being held.
How do you want to go about the Fifth Child's synch test?
Misato:
Let's hold off on the trick questions today
and get a straight reading on what he's capable of.
That being...
FUYUTSUKI:
Who would have expected that he would synchronize with Unit 02
without the core being reconfigured? This boy...
IBUKI:
But this is beyond belief! This should be impossible, given the system.
Misato:
Nevertheless, these are the facts.
First, accept the facts for what they are,
and then investigate the why behind them.*
Misato continues to investigate in her spare time...
Misato:
And yet, we still have no idea what he is.
Who in the world is that boy?
Who, indeed?
* Maybe it's just me, but Misato's words here always seemed to resonate with the beginning of #21':
Man A "You mean the Super Solenoid Theory that Dr. Katsuragi proposed?"
Old Man B "It's just too far-fetched!"
Old Man C "And it's still in the hypothetical stage."
Man A "But only the S2 Theory can explain the motive energy of that giant."
Man D "We already have actual proof, however unintentionally."
Old Man E "The fact that it exists means that it must be accepted."
Old Man B "I'll accept it when, and only when, all of the data's been verified."
! 
