Ok I'mma list my Hellsing ships because it's a fandom where I have a fair number of them.
Alucard loves Integra from the moment he's aware of her- literally his first taste. He wants to sire her, but more importantly, he wants to please her. He wants to fulfil her orders and make her embrace the fact that even though she isn't a creature of the night at first, she's a natural born killer. So he serves her as she grows up, he protects her and does her bidding in the hope that one day she will finally embrace the night. He even allows for the chance that she'll find someone else and fall in love while alive, thus scuppering his chances of siring her (IMHO, at least). I also don't think it would actually take him all that time to kill all the souls inside him: my theory is that once he had killed a fair number he realised he was in the Hellsing mansion and had a fair idea of what was going on, so kept Schrodinger around for entertainment before killing him as Integra was approaching the end of her natural life. He offers vampirism to Integra as a gift, having lived most of her natural span.
Pip x Seras
Need I really say more? He dies trying to save her, and she in turn relinquishes her last vestiges of humanity so that he'll forever be a part of her (excuse the pun), before exacting horrible, horrible revenge. Fuck y'all, Zorin.
Young(er) Integra x Seras (pre-Pip)
I think that Integra probably does develop some feelings for Seras (see the feeding scene), and that it's part of her coming to terms with her undisclosed wish to become a vampire and her attraction for Alucard. Integra sees Seras coming to terms with her new 'monster' status and recognises a kinship, although probably not on a conscious level. Had Pip not become part of the equation, this could have gone further.
Girlycard x Young Walter
Explanation: Walter was a teenage boy who could keep up with Alucard in a scrap, and Alucard has a thing for genuine humans slaying monsters. Walter, when he's older, sees Alucard as he is normally all the time, and is familiar enough with Baskerville to dismiss it out of hand when battling Alucard, but when it comes to time to defeat Walter and drive him off, only Girlycard will do, as that was the form that so admired young Walter and must be the one to spurn his artificial return to youth. If Walter fights standard Alucard, he fights the monster that dares chide him for returning to youth when he doesn't have to bother about ageing. Fighting Girlycard, Walter goes back to the little boy that fell in love with someone who so praised his capacity for violence.
Fighting the psycho ex-lover from hell, literally.
The Captain x Heinkel Wolfe
Ok so for starters I never noticed the name connection there before, for seconds: Since when do Nazis who participated in the Malmedy massacre spare their opponents by shooting them in the cheek, and why the fuck is a regenerating werewolf carrying around a first aid kit?
I think that will do for now...
