The Case for AxI
There is a lot of bad AxI fanfiction out there, and by "bad" I mean "unrealistic and out-of-character."
If and when these two do get together, there's going to be no running together in slow motion across a field of flowers. There will be no cute nicknames and neither one will allow his/her personality to be compromised. And above all, it will happen slowly.
But the seeds of a romantic relationship are already there, in the form of adeep and intense friendship that both of them would deny if you asked: there's lots of tension and lots of bickering between the two, but they're closer than they would care to admit.
Let's look at the evidence. (All quotes are from the dub except where otherwise noted.)
Exhibit 1 (Order 03)
During a discussion of the FREAK chips, Alucard calls chipped vampires "man's cheap imitations." Integra accuses him of pride, then asks just what the difference is between the chipped fakes and the real deal.
For once, Integra seems to have provoked Alucard enough that he visibly shows it. He doesn't respond. A minute later, Integra apologizes.
It's her only apology in the whole series, to anyone.
She doesn't directly say "I'm sorry," but she says "I know you're nothing like those creatures. It was uncalled for." This is also one of very few, if any, times when she admits to being wrong. (He does respond to this: "Then why did you feel the need to say it? You humans are incomprehensible.")
If Integra really disliked Alucard, she would've followed up on her advantage; if she didn't regard him as any more than a heartless monster, or an inferior, she wouldn't've bothered to say more. But she has enough respect for him, and enough concern for his feelings, to apologize.
Exhibit 2 (Order 04)
Now, I admit, this incident just downright puzzles me. But it's an interesting example of the depth of the intrigue between them.
The setup: Walter and Integra are having a discussion when Alucard enters and asks for a bigger gun. (Don't even get me started on the things you can read into that.) Walter promises to get him one; Alucard says "I look forward to it" and starts walking off, when Integra starts to say something: "Alucard."
"I can't help you," replies her vampire, without turning around. "I belong to a world where all is death. Your world of choices was not meant for me to inferfere with."
"My world is your world."
Alucard turns back to face her and touches his hat: "And a good evening to you, Miss Hellsing."
What was she going to ask?
Exhibit 3 (Order 05)
The scene: Hellsing's human troops have just been sent after the Valentine brothers, and Integra's walking down the hall when Alucard drops down out of the ceiling and wonders why he didn't get to go along. (For one thing, he wants to try out his new gun.)
Integra points out that these vampires have human characteristics - the subtitles say human cunning - that "it might be difficult for a creature like you to comprehend."
To which Alucard replies, "That sounds like it could be a lot of fun."
We already know he considers humans "incomprehensible" but that doesn't seem to be a bad thing. In fact, it has a kind of allure.
Exhibit 4 (Order 07)
It's worth pointing out that, when they need to, Alucard and Integra can pull off flawless teamwork. Consider this scene from the National Gallery, in which Integra and Maxwell are meeting.
They've gotten passed the "pleasantries" and Enrico's just thrown in his "squealing English sow" comment. Integra just smiles - it's her 'you're going to die now' smile - and then Alucard walks out from behind her.
"What nerve. You dare call my master a sow? Really, I don't see how I can let you leave here alive." (And you know, if he isn't serious about that, he sure sounds like it.)
One implication of that, by the way, is "Nobody insults my master but me." But Enrico has never seen these two bickering, so what he gets is "Mess with Integra, mess with her vampire." (Accordingly, he relocates himself to be behind his companion, Father Renaldo.)
Exhibit 5 (Order 08)
When Alucard knows that there's a big bad undead coming and he's the only one who can deal with it - when, for the moment, he's indispensible to Hellsing - and when he also happens to be messing around in Integra's dreams . . . what does he do with this relative freedom?
Well, aside from showing off with fancy light displays, he ties the lady up for a bit.
If that doesn't say "kinky," I don't know what does.
Exhibit 6 (Order 08)
Now this is where things get interesting.
Alucard's been pretty excited about this upcoming battle with a powerful vampire, so he sneaks out of the house in dog form and has a little rendezvous with Incognito. It looks like they're gearing up for a generic little battle, although for once Alucard's doing all the talking: commenting on how they're both servants, so they might as well have a little fun with this battle. Incognito stays menacingly silent.
Meanwhile, everyone's favorite baobhan sith has hypnotized her way into the Hellsing mansion, and at this point she has Integra paralyzed at her desk with neck (among other things) bared. But Alucard's so preoccupied that he doesn't pick up on her distress until Incognito remarks, "The two of us - we are different. The difference is that you don't have a master any more."
And Alucard freaks out.
Even on a normal scale, he freaks out. Which, on the Alucard scale, corresponds to complete and total meltdown. He shouts, he shoots, he zooms back to the Hellsing mansion in the company of the second most massive glowing-sigil-from-his-gloves in the whole series (it's second only to the one that appears over all of England in the end).
Note that this is the first time all series that Integra has been in serious, iminent danger which she can't (as she could in the case of Jan Valentine) personally take care of. It's unexpected. It makes Alucard uspet. He may not like being Integra's servant, but it seems he'd rather be her servant than be free at the cost of her life.
Exhibit 7 (Order 10)
During the flashback, when Alucard has young Integra up against the wall and is busy trying to scare her, when she's already tried shooting him and it hasn't worked, when she doesn't know that he's under her control, when they don't know each other yet, and when she stands her ground anyway . . .
. . . he says in no uncertain terms that she turns him on.
The dub's line is "You make my blood boil," but if you check the subtitles, the more exact translation is a lot less vague.
Exhibit 8 (Order 10)
Integra's just coming out of the flashback/dream, and Alucard, who's been watching (remember that appearance he made in the mirror at the beginning?), says hello. They have a brief conversation. They both smile.
And, yeah, Al can't resist the chance to get one off on Integra (note the subtitles, "You're still a little girl, just like you were back then"), but she doesn't snap back. For once they're both perfectly relaxed, neither one on guard, and the result is a surprisingly tender moment.
Exhibit 9 (Order 10)
Throughout the emergency surgery in this episode Alucard is standing near the operating table, watching.
Seras is there in the beginning too, and the two vampires have a short conversation. This is when Seras learns that, just as Alucard is her master, Integra is his. The idea unnerves her; she starts to say something and looks up at Alucard, but when she sees the look on his face the words die on her lips. Instead she leaves.
Seras' attachment to Alucard is not only that of servant to master; she has something of a crush on the guy. To learn that Alucard has the servant-to-master attachment to somebody else really rocks her world. Moreover, as she has yet to separate her feelings for him as her Master from her hero-worship in general, she's probably unsure just how strongly Alucard is devoted to Integra.
Seras' discomfort, however, is not Alucard's concern here. Although he steps in at other times to prod his fledgeling in the right direction, he doesn't bother with her at all this time; his entire attention is focused on Integra. Which brings us to our next exhibit . . .
Exhibit 10 (Order 10)
Alucard stays by the operating table through the entire surgery. Not even Walter - who is completely devoted to Integra - does this.
Of course, Walter has no doubt that she'll survive, and Alucard probably isn't worried about that either. So why hang around? One option is that he cares more deeply about Integra's survival than even Walter, which is pretty darn deeply.
Perhaps it's curiosity about her dream, too - but that's not all. Integra is going through, in her dream, an old battle for her life, which becomes a metaphor for her current battle for her life; Alucard watches, but he also throws in a single comment: "I know you don't want to die tonight."
This isn't part of the actual incident that Integra's remembering; at the time, Alucard hadn't been revived yet. So this is the present-day Alucard interfering with the present-day dream, meaning he's talking to Integra about the struggle she's going through right now.
What, then, is his reason for hanging about? Moral support.
Exhibit 11 (Order 10)
The support Alucard gives Integra during the surgery continues until just after it. He does leave right before she wakes up, so there's no touching "the first thing she sees when she wakes up is his face" scene. Not that you'd expect that from Alucard anyway.
No, the first thing Integra sees is, quite sensibly, the doctor saying "You're going to be just fine." But the second thing she sees is the door swinging shut.
She knows full well that Alucard just left.
He could've just walked through the wall, by the way. But he walked through the door just late enough that she'd see the physical evidence that he was there.
And she closes her eyes and smiles.
This is the second of three incidents of present-day Integra smiling, not counting 'you're about to die' smiles. One of them was caused by Walter; the other two, by Alucard.
Exhibit 12 (Order 11)
This is the most concentrated scene of Alucard and Integra's closeness; it's short, sweet, and to the point.
Seras, having just woke up from a nightmare, is wandering the mansion when she sees Alucard on a balcony through a partially open door. She smiles and moves forward, starting to say "Mast-" . . . and then stops and looks distressed.
As she got closer to the door, she had seen that next to Alucard was Integra - not too close to him, but not too far away, either.
It's obvious to Seras that this would be a really bad time to cut in. Alucard and Integra are sharing a private moment together, in which there's no room for a third wheel.
Exhibit 13 (Order 11)
There's a big royal ceremony coming up, and Integra's arranged for it to happen at the Hellsing mansion. Before it starts, though, she goes down to the basement and seeks out Alucard.
He speaks first: "I've been wanting to ask you something."
"Have you ever thought about asking me to drink your blood? Have you ever thought about mixing your blood with mine, about becoming more than you are?"
"Why don't you just read my thoughts?" replies Integra coolly. (Note, however, that she doesn't say 'no.' Although she has no intention of admitting it out loud, she has thought about it.)
"I have," says Alucard with a grin. "I just wanted to hear it from you."
If you read Dracula, Carmilla, or pretty much any analysis of vampire works in general, you'll pick up that vampirism is of a very sexual nature. The vampirism-related tension between these two - and therefore the sexual tension - is high. It's especially high in this scene, as they usually don't come this close to the topic; but though usually unspoken, it's always there.
Exhibit 14 (Order 11)
Later in the same scene as the previous exhibit, Integra comes to the topic that she really wanted to discuss: "As head of the Hellsing family, it's the first time I've been given this honor [of participating in this ceremony]." It's just a statement, not an outright admission of insecurity.
"I remember your father performing this same ceremony," replies Alucard quietly. It's just a statement also, but there's an unspoken compliment implied: you remind me of your father. "The timing is bad. It's too much for you right now."
"I know." (Integra's still recovering from surgery, remember.) "Which is why I have to attend."
"I know." They understand each other.
As Integra walks off, however, Alucard calls after her: "Don't you want a taste of my blood before you leave?" (She stops for a moment but doesn't answer, then continues walking.)
Alucard brings up the topic after it's been dropped; he pushes the issue; he tries very hard to get an answer out of Integra. Since she's already implied that the answer is no, he's trying to get an answer of yes. He's working hard at this.
Two possible reasons present themselves: (1) he wants to protect her, by making her strong enough to survive the enemy that's about to show up, and (2) he would absolutely exult in the experience.
Or possibly both.
Exhibit 15 (Order 13)
As the second phase of the big epic climactic battle rages in the skies over London, Alucard's powers are all released and Incognito has gotten ahold of a handy demon from Hell to help him out. On the ground, pretty much everyone on both sides is dead; Seras has just found Integra.
This woman has been dropped out of a helicopter, pinned by axes to a floor, used in a demonic summoning, and chewed on. Plus she's still recovering from surgery. This has really not been Integra's day.
And her first question when Seras gets to her is, "Where is Alucard?"
She saw Walter crash in a helicopter that subsequently exploded, and she heard Incognito boast that Alucard was actually dead; the first one she asks about is Alucard. Odd, that.
Viewers are encouraged to volunteer their own eyewitness testimonies; these can be found at the Witness Stand.
This is the summation of evidence I've gathered from the anime. Combined with the manga evidence, the obvious conclusion: AxI is a reasonable, realistic, and even very likely pairing. The defense rests.
The Case Against
The Witness Stand