Yo, guys! Ideas just flooding my thick little skull!
So, here's the plan. Every time one of my or your OC's have a birthday, I'll write a little shortstory.
Zack's birthday is the 16th, which is today here in Britain, but, I couldn't wait. And, Twilight, your birthday was informed upon me too late and I hadn't had the idea then. SO, when Silent's birthday comes, I'll do a joint party for you two!
This story will have ShadAmy, Zack x Silent, Mighty x Twilight, Spark x Destiny, Tails x Cream, Silver x Blaze and an idea- I'll add a little something onto each character to make them more awesome for every birthday, as my own little gift!
How's that? Good, uh?

Zack's Birthday
Well, Zack had certainly chose the location well.
The party was taking place in the city hall- with it's huge main room with the fountain in the middle and access to a huge dining hall containing a table overrun with food of every kind, and the fact that all his friends where invited, and the insane speakers ready to blast music on the ceiling, but mainly, in Zack's mind, that tonight was the night he went after his love.
Love spells where useful- in fact, he had laid one onto the ministress of the hall to get it for his birthday- but he had always felt that he didn't want one on Silent. He knew she loved him, and she did. She just struggled to show it.
Zack was planning to ask her to dance with him when the nice music came on, and Spark was acting as his wingman. The other hedgehog had provided backup and support for a month now, and Zack knew he had Spark behind him. Zack finished setting up the rest-between-dances kind of tables (You know, the rest break ones where everyone watches the love action happen) and had a quick check of the room. He liked it- not the sort of place where it's just loud, booming music all the way through. There was going to be love here tonight.

Tonight
The guests where arriving. Spark and Destiny had immediately gone to help themselves to the wide array of food almost instantly (They both shared a passion for mass food consumption), Silent, Twilight and Twix danced next to the fountain, a couple of Zack's other personal friends joining in, and Cream was with Tails, trying to entice him over there with them. Twix was dancing with her little pet chao she had brought with her and looked pretty happy. Not that it was unusual.
Silver and Blaze had gone off together a few minutes ago, to the bedrooms (Zack decided to leave them alone for a bit), Mighty looked to be building up the guts to go and speak to Twilight about his crush at long last. Everyone was enjoying themselves, and Zack was happy. A prod on his shoulder snapped him out of his trance and he turned to see Spark, holding a plate piled high with food. Literally piled high- you couldn't see the plate.
"Are you gonna talk to her, or what?" He said, choosing a little cupcake-looking thing and unwrapping it.
"I'll do it later when the music I chose came on. Shouldn't you be with Destiny?"
"She's getting her second plate."
"Oh. That's... a lot of food."
"You call that a lot? This is my third. When you spend your life processing raw energy, you have an appetite."
"But... Destiny doesn't HAVE any powers."
"I know, a natural appetite. That's one of the many reasons I love her." Spark took a sausage wrapped in bacon and ate it whole.
Spark turned and walked over to Destiny (Who had just emerged from the dining hall, plate in hand) when Zack facepalmed.

Looked like Cream had succeeded- her and Tails where hugging tightly, sitting on the wall around the fountain. He looked to be saying something to her, and saw Cream giggle. He smiled and directed his attention to Silent. She looked like she was having fun, but in that own way of hers. She was sort-of smiling.
The song changed- to the one Zack had chosen- Greensleeves, by David Nevue. He glanced over to Spark, who gave him a thumbs up.
Conveniently timed, Mighty had gone up to Twilight and they where dancing together, Twilight never looked happier in her life. Zack walked forward to Silent, who was now sitting on the wall of the fountain.
"Uh... Silent?" Silent looked up at him.
"Can we, maybe... Dance together...?" He was nervous, more so than when he asked her out. Suddenly, she did something no-one expected. She smiled, possibly for the first time ever, and stood up. She took his hand and wrapped her arms around his neck, while he held her waist with his free hand, and they slowly danced back and forth, staring into each other's eyes.
Spark smiled and him and Destiny went up there, dancing alongside them and Twilight and Mighty. From the other side of the room, Amy, who had no choice but to spend the night on her own, was approached by a figure.
"Um..." Said Shadow, making Amy look up, "Can I... have this dance?"
She smiled and he took her to the dance floor, while the other personal friends and guests whistled in approval. Soon, four couples where all dancing, dancing until the song was over.

Twilight had taken Mighty out to the balcony- now lit with bright stars- and Zack could see them, kissing passionately. Silver and Blaze had returned (Both looking suspiciously flustered) and they went to the Dining Hall (Followed by Spark and Destiny). The other two couples- Shadow and Amy and Zack and Silent- stood, still in the romantic dancing position. They mindlessly stared into each other's eyes, entranced by the beauty of their partner.
Zack and Silent both leant in for a kiss; and kiss they did. Shadow was a little slow to make the first move, so Amy did it for him (Much to his surprise).

The stars where visible through the clear windows of the great City Hall as the two young couples kissed, and when Zack and Silent broke the kiss to stare back into one another's eyes, they each saw something more precious than all of the stars.
They saw love.

The blush on Silent's face when she reads this will be Instagram material.