OK, here is an idea that's been going through my head for a while.
Please keep an open mind and hear it all before you judge. Throw away your preconceived notions.
I think Alistair and Tanya would make a perfect match.
To me Alistair is like an older version of Edward, after losing his family and a few centuries of "justified" human hunting.
I imagine Alistair has a reverence for the idea of innocence and he tries to use his gift to hunt only human monsters just like Edward did. (maybe he was a skilled detective in his human life, like Sherlock Holmes
, tracking down a real vampire, just like Carlisle)
And that's why he has such admiration for Carlisle, because of his pure uncompromising innocence.
Maybe they met in England while Carlisle was still very young and looking for a friend. (I doubt they would have become friends after Carlisle spent a few decades with the Volturi)
But Alistair can't share his blind faith and his fierce determination to lead a good life.
That's why staying with Carlisle makes him uncomfortable, guilty or even depressed.
Maybe he even fears to corrupt Carlisle with his own presence, and that's why he keeps his distance.
Maybe Alistair lost his family/coven to the Volturi justice the way Tanya lost her mother, and maybe he blames himself for that. (Maybe he found evidence of the Volturi corruption, and his family got punished for that
) It would explain his terror and suspicion of the Volturi, and also why Bella perceives him as misanthropic. He is pragmatical, mistrusting, hopeless, grieving, self-loathing and unwilling to form a bond with anyone again.
Now what if Alistair didn't leave the Cullens before the fight out of cowardice.
What if he actually went to Volterra, to use this one and only chance to search Aro's personal archives,
trying to find out what really happened with his family and also uncovering the truth about Tanya's mother in the process.
Maybe she was innocent or at least explained her motives.
I can imagine Alistair and Tanya bonding over that, especially now with Irina dead and Kate having just found Garrett.
And I think Tanya might enjoy the challenge, since she couldn't seduce Edward.
I think people, especially vampires, don't become misanthropic, unless they have a very decent heart, that's been hurt too much. (who would want to turn a misanthropic and mistrusting human
And I can see Tanya changing him the way Bella and Nessie have changed Edward.
Also think what this could mean for the Cullens, having a gifted tracker in the family. (extended though)
No more enemies hiding around, like with Victoria creating her army in Seattle.
And they will be able to find all their friends much more quickly the next time they need to gather.
Now I know many of you see him as an ugly old grouch. (like Mad-Eye)
But he was never really physically described, whether he is beautiful or not,
and wouldn't it be ironic if Bella found an older version of Edward so little to her liking?
I mean comparing Alistairs muttering to Midnight Sun, it's almost like Edward is speaking his mind for a change.
And sulking in the attic was exactly what Edward did in New Moon.
Now don't say "some things cannot be heard".