Albus has a secret.
...
It is not a large secret... smaller than the average table: about as large as someone's head (not that that's surprising) and smelling of dust. It isn't someone people normally talk to.
...
He struggles to fit into his house, quite a lot of the time. Professor Longbottom is of the opinion that he is Slytherin's very own Hufflepuff... but Albus isn't as happy as Uncle Neville seems to think he should be at that suggestion. It's just not quite right for him.
The hat chose him because it couldn't put him anywhere else.
He's not brave.
He's not intelligent: he's a bit scatty, actually; not very clever when it comes to working things out. Albus does his work slowly. Just because he tends to keep his nose in books says less about the fact he's dedicated to his schoolwork and more about the fact he hasn't got any friends. (His secret understands that: his secret had that too.)
He'd rather sell someone out than be loyal to them, and won't work hard unless it's for his own benefit. Getting all Os in NEWTS isn't going to help him: it's just going to make him stand out. He's never been loyal to his family, either... very much. He's too wary of James. He'd rather put permanent dye in the water tank and see his brother's skin turn blue so that he knows there's a prank war, rather than wake up, get in the shower and find out by the navy blue of his skin that there is one.
He is Slytherin, then.
He is cunning... hence the pre-emptive pranking.
He is ambitious... not to get caught.
He has no morals... yes he will do whatever it takes to get away from James. James is a prat, and also his brother. He needs to have no qualms about whatever method he could use to escape.
Bar murder.
Which is acceptable in some situations.
Also, Albus is a pureblood.
...
But, anyway.
His secret doesn't care about any of that. His secret (snarky, funny, accepting, clever, also a Slytherin) understands.
Why couldn't there have been a house for lonely people who don't make friends easily? He'd have fit into that one, no question.
Oh yes, his father is proud of him. His father is proud of everything he does, including falling forwards into his 6th birthday cake and crying miserably at James.
That's another thing. His secret knows a James too. His James is almost the same.
More obnoxious. More thuggish.
Hearing about the other James makes Albus glad he hasn't got him as a brother instead. James is unbearable at the best of times, without being cruel with it... although, with his luck, they and the first James are probably related in some way or another...
...
The portrait was in the Headmaster's office... but then it'd been taken down.
They had all been taken down. Professor McGonagall announced one day in the Great Hall to stuff tradition, they'd all been giving her a headache, so they were being taken down and put somewhere else.
It's lucky Albus found that somewhere else for one of them, at least.
...
Everyone knows where Dumbledore is: people nod at him on their way into the Great Hall.
Armando Dippet is placed up by the Hufflepuff common rooms: he's always liked a chat, and Hufflepuffs are always, it seems, ready to give him one.
Phyllida Spore can't sit near the greenhouses, but would've liked to, as, before her professorship, she was an avid herbologist. Instead, she makes do with a seat outside Professor Sprout's private quarters.
Walter Aragon, a Care of Magical Creatures enthusiast, sits near the owlery.
Quite a lot of the portraits have been attached to the banisters on the stairwells (they were running out of space) and even more set to line the classrooms.
It seems like there are more Heads than pupils at Hogwarts, some days...
...
Albus found his secret in a broom cupboard.
...
It isn't a very large broom cupboard, and it doesn't have a lot of brooms in it, but it's dark (which he likes), warm, and free of spiders. Also, it has a chair in it for some reason.
Across him, in the broom cupboard, sits the 1998 Headmaster.
He doesn't know his name: he's just 'Headmaster'.
It suits the both of them.
...
It takes a lot of stairs to climb to the 7th floor corridor, and he can't always find the cupboard on his first try... but it's worth it.
After all, his potions grade is going up and up and up...