Hey everyone,
This story is going to be AWESOME! I thought this one out for the longest time, a week to a fortnight or so, and I loved every aspect of it. It has a really caring Sirius, who still worries if he's being the right kind of father, it brings a few background characters more to the forefront and it has Sirius-Harry father-son love.
I am loving this,

Venquine1990

Preview #21
Sirius Helps

20th of June 1994
London, England
Harry's POV

I just made sure to let my uncle know that I have a godfather that actually cares for me and scared him with the knowledge that my godfather is supposed to be a dangerous criminal from my world before going with him back to Little Winging, yet as we cross through London, do I suddenly notice something along the way.
"We're approaching the Leaky Cauldron. And – I can stay there for the rest of summer and maybe – find someone who will listen to me about Sirius." And instantly I turn to the front of the car and say: "You know Uncle, I probably won't have to keep convincing my godfather that I'm doing well – if I don't have to go with you."
Yet then I get shocked by how uncle responds as I instantly get the relieved feeling over the fact that I am buckled up in the backseat as Uncle Vernon makes a mad dash for one of the parking spots on the road, the road itself being only a few blocks away from Charring cross Road and he turns to me and furiously snarls:
"What do you mean?" And I say: "I mean, we're only a few blocks away from an entranceway into my world I stayed there for the better part of last summer too. I won't mind staying there and if I do, you won't get tempted into doing something I will feel like reporting to my godfather. You know, the mass murdering Sirius Black."

Uncle Vernon turns even more purple with anger at my hidden threat and then snarls: "Get out." At which I reply: "With pleasure." Feeling exuberant over the fact that I get to spend my upcoming summer the way I want to and excited over the idea I might get another chance at clearing my godfather's name.
I unbuckle my seat, trying not to wince at the burning feeling in my neck where the safety belt had been cutting into my skin during my uncle's mad driving and I move over to the back lid of the car, pulling my trunk and owl cage out and quickly shouting: "Have a nice summer." Before closing the lid on the car.
And instantly after Uncle Vernon drives off with a mad speed, almost causing himself to drive straight into three other cars and I cringe at this, part of me wondering if I will care more for Vernon or the Muggles he might hurt if he had crashed his car into theirs, but then shake my head when he shouts at them to watch where they're going.

"Sorry you had to experience that, Hedwig. At least we won't have to be bothered by him or the others anymore this summer – that is if Dumbledore keeps his nose out of all this." I mutter at the end and I then carefully set her cage on my trunk before starting to drag it down the blocks leading to my new destination as I say:
"Let's – ugh – hope that – whoo – we can – hah – find someone who – who can – Merlin's beard! I forgot how heavy this thing is." I mutter to myself at the end and quickly drag the trunk over to a small side alley before I open Hedwig's cage and ask: "Hedwig, you think you can fly to the Cauldron and get someone to help me?"
And the owl looks at me as if I am insulting her skill, making me smile at her as I say: "I know you can, but you need to be inconspicuous. You know, due to the Statute and all and it being day out." The owl nods and then flies up, using the small side alley and the shadows caused by balconies to disappear down the streets.
At this I lean back in relief, also glad that Fred and George managed to smuggle some Butterbeer with them from Hogsmeade before the train left and that they hid a few in my trunk. I open the trunk and pull out the bottle in question, amazed that the beverage still looks as if I just pulled it out of the fridge and I pop the lid.

The drink is delicious and the coolness of the beverage feels wonderful to my sweaty skin as I had only managed to drag my trunk one and a half block down from where Uncle dropped and I sigh in relief after my gulp before quickly checking the main street to make sure no Muggle is noticing the teen with the weird trunk.
Luckily enough do the people on the main street seem too busy with their own shopping, business and lives to even look into the side alleys down the street and then, just to be safe, do I turn around and take a quick, cautionary glance down the alleyway, not trusting it not to have some shady characters like the ones in Knockturn Alley.

"Harry?" I suddenly hear and I turn around again, glad that I couldn't spot anyone from where I'm sitting and I see a Hufflepuff girl with a long plait down her back as well as a woman standing behind her, who has a monocle over one eye and Hedwig on her shoulder and who does look like she's related to the girl my age.
"What are you doing here? Shouldn't you be heading home?" The girl asks and I want to roll my eyes were it not for the fact that I know that only Ron, Hermione and a few select Weasleys know how much I detest staying at the Muggles and I say: "I would have, if I had a home to head to. I'm here because I don't feel like – well going."
"You mean back to the Muggles you ran away from last summer, Mr. Potter?" The woman asks and I shrug as I say: "I was ready to just accept that Dumbledore doesn't accept that for an excuse, but then I realized that I was close to the world I actually belonged in and – I just took the chance. Not my fault those Muggles detest me."
"And vice versa." I think to myself but don't voice and the girl turns to her relative before turning back and says: "You know, my aunt and I always get something to drink at the Leaky Cauldron before heading home. You can come with us if you want." At which I smile at the girl, feeling she is doing her House honor and say:

"That's why I send Hedwig ahead. Pushing my trunk ahead on a trolley is no problem, but – the thing itself is just too heavy for me to drag it all the way to the Cauldron, which is strange cause last summer I was able to drag it down several blocks when I ran away." At this the girl giggles and the lady's lips twitch as she says:
"I can only imagine that was because of the adrenaline you were feeling at the time and the reason behind it being heavier now – I can only imagine that your friends bought you many different gifts when they were in Hogsmeade." At which I nod at her and then see the woman checking the Muggles as she pulls out her wand.
She then waves it at my trunk and I feel it shrinking under me, making me quickly get off it and see it turn the size of a matchbox, much to my amazement. "That ought to do the trick. Now, Mr. Potter, do you have any idea why your owl chose my niece and me? The Leaky Cauldron was quite crowded, you know."

At this I look at Hedwig herself, the owl waving one wing at me and I look down, remembering what I had in my hand before getting in the car and I look at the woman as I ask: "You don't work for the Ministry, do you ma'am?" And the woman gives me the desired answer: "I head the Magical Law Enforcement, actually."
This makes me look back at Hedwig, who hoots and gives me the owl-equivalent of a wink before she flies over to land on my shoulder, her claws digging into my shoulder in a comforting way and I turn from her to the woman in front of me as I pick up my trunk and say: "Well then, ma'am, do I have a story for you."
At this the woman raises a curious eyebrow and then the girl says: "Trust me, auntie, wherever Harry Potter goes, crazy adventures follow." And I remember what I always think when hearing that: "I don't go looking for trouble, it always finds me." At which I snicker and then start walking alongside the woman and her niece.

Now this is awesome.
So Amelia will be one of the canon background characters – who in canon only came about in Order and was actually killed in Halfblood – who will be playing a more prominent role in the future and yes, I know, there was no sign of Sirius helping just yet, but that is because I haven't reached that part yet.
Sirius will be helping Harry a lot, he will be helping him settle down and realize he has family now, he will teach him that putting himself in dangerous situations – even if he doesn't have much of a choice – he will help him when the Tournament comes round, he will just be doing so much, but not just for Harry, for himself too.
Hope you enjoy,

Venquine1990

Further Story Parts:

Harry reports to Madam Bones and agrees to let a Dicta-quill, drenched in Veritaserum, write down a witness statement about everything that happened in the previous year

Madam Bones convinced Fudge to hold a Wizengamot meeting without Dumbledore and then tells Fudge exactly how he can accept the truth and not lose office for acquitting Sirius

Sirius, James and Peter actually did register their Animagus forms in 1976, but did so in secret reports with the intention to make the reports public once the war was over

Albus, Minerva and members of the Great Alliance find out how their actions – or inaction in regards to the Alliance – effect Harry and that they will have consequences for the trust and respect he has in them

Harry and Sirius both hire Ted as their Mind Healer to help them past their traumas; the Dementors and bad Muggle treatment for Harry and Azkaban and Halloween for Sirius

Harry and Sirius stay at Sirius' old apartment for nine days to represent nine events for which Sirius feels Harry should have been grounded before they move to Potter Estate

For his birthday Sirius takes Harry and a select group of friends to a Muggle amusement park

Harry and Sirius move to Potter estate, Hermione and her family move to Sirius' old place and Percy moves into the Grangers' home

Instead of working for Crouch does Amelia hire Percy to work for her and her Department instead

Godric's Hollow, due to being called a monument and then left to the wolves, has been ransacked of anything and everything that once belonged to either Lily, James or Harry

Horace Slughorn doesn't just know of the Horcruxes, he also knows of a special potion that destroys the soul but leaves the container intact. Sirius gets this out of him by having him meet a portrait of Lily and James, yet after his confession, revealing the recipe for the potion and handing over a sample, does Slughorn let himself get Obliviated

Knowing of the Tournament and predicting that Voldemort will try and use it to get to Harry – who is still undergoing his Mind Healing Treatment by Ted – does Sirius pull Harry out of Hogwarts for the year, yet convinces Albus to make up a little white lie to the students

During the World Cup Finale does Harry take a bath in which Snape and Dumbledore switch the water for the potion and with this does the Horcrux in Harry's scar get destroyed without him ever knowing he is one

Lucius provides Albus with the Cup, Snape helps him get the Ring and the Snake and Sirius helps him get the Locket and the Diadem

During the attack on the World Cup, Harry believes he sees Sirius fall to a deadly curse and unleashes a wave of magical energy that attacks anyone who has ill, murderous or torturous intent towards those at the site, attacking almost all of the Death Eaters that are there, bar Lucius who reformed after realizing what he unleashed upon the school during Chamber

The magical wave of energy also effects the Dark Marks on all Death Eaters in such a way it weakens Voldemort to the point of dying as he tries to sustain himself through his connection with Nagini, yet he drains her of her own life, thus killing the Horcrux and himself