This is a thing Sashi and I came up with for fun. It includes both the Fab Five and Dynamic Duo in here. These are merely concepts and they're still being worked on as the rest of it will be a group collaboration instead of just the two of us. It's also based on movie-verse, not comic-verse, for your future reference.
First point: we're all somehow connected to a canon character, except Thor and Steve. Thor because he's a demi-god and Steve because...he's a virgin. Moving on.
We decided Koondy and Shii will have a connection with Clint and Nat. The latter duo was sent on a mission near a place where Koondy and Shii's class was having a field trip. When danger of the mission unfortunately involved innocent civilians, including the class, Koondy and Shii (as well as their peers) were rescued by Clint and Nat. Out of an act of bravery when she saw Clint fighting, Koondy took a legitimate bow and arrow she had found lying around at the amusement park her class went to, and took down one of the enemies flawlessly because she takes up archery as a hobby. Clint was rather impressed at her skill, technique, and guts.
Shii was so awestruck by everything that she said, "I want to join your team." and is actually closer tied with Nat than she thinks. Shii's parents are spies for S.H.I.E.L.D. themselves so she was able to track down Nat fairly easy. Her parents made her take a lot of martial arts classes to defend herself since they were "on vacation" a lot, so she already had the potential. Clint and Koondy actually have a better relationship than Shii and Nat. The first pair get along swimmingly after a while and in a way, even though he's her mentor, Koondy considers Clint like a father figure. A lot of the time after training they go have ice cream and bond, father-daughter style. He becomes really fond of her. Nat on the other hand isn't as open. She's more distant with Shii, and vice-versa. Nat trains her to be a spy but they don't show affection openly like Clint and Koondy do. They care about each other, but it's very subtle. Koondy has a crossbow attached to her arm which maximizes her aim and quickens her defense. She also uses darts (some with poison) as well as other projectiles, and bombs. She also learns self-defense from Clint in cases where projectiles prove futile. Shii gets all the cool spy gadgetry, including the sexy suit (can be modified for a camouflage option) and infrared goggles. She also has gloves that copy any human fingerprint so hacking comes easier, and she has two firearms, in addition to her physical prowess.
Tsuna and Sashi will have a connection to Bruce. They're his adopted daughters and they travel with him to whatever remote location he decides to go. Sashi was found first in Haiti. She has the power of bone manipulation and uses them to fight but it also allows her bones to reconstruct increasingly fast. She can also control the bones around her and she can also do magic with them. Her powers aren't very controlled yet as she needs to stay hydrated and in a calm state of mind for them to be neutralized. Because she was dehydrated constantly, her powers would go haywire and people would be afraid of her so she was ostracized and had to forcibly drag herself to a body of water to keep cool and her powers under control. She was given the title, "Skeleton Girl" and everyone was afraid of her because of how horrifying she looked when her ability wasn't kept in check. Bruce found her hiding on one of his trips to Haiti when he heard rumors of the "Skeleton Girl" and after he had gotten a firm grasp of her situation, did he decide to take her under his wing. Her father was a hoodoo priest but he abandoned her and her mother. She was basically orphaned when her mother died.
Tsuna on the other hand was a lab experiment in the depths of the jungle in the Yucatan Peninsula, Mexico. The project was to find a way to give humans animal traits to enhance their mortality. She was selected to be a part of the serpentine and avian experiments. Very few survived, but her health was top-notch to begin with (as well as her willpower) and she withstood the pain that came from the first few days she was experimented on. She ran away when officials discovered the lab and hid in the jungle, using her animal instincts and the resources around her to survive. Bruce and Sashi had went to a village in Mexico and it is there that they discover Tsuna trying to steal food. Sashi notices she's kinda sickly so she gets Bruce to aide Tsuna. He actually made some medicine to adapt to each of their conditions and actually didn't want to take them because of his obvious fear, but when he realized Tsuna and Sashi were happy in each other's company, he decided to become their adoptive father. Tsuna can either turn into a serpent-like humanoid or an avian-like humanoid, has all the traits of said class of animals, but she can also morph into them both to become something reminiscent of Quetzalcoatl from the Mesoamerican folklore.
Speedy and Bats already know about S.H.I.E.L.D. because they'd be agents before the rest of us meet them. Sashi and I decided to make them the nieces of Coulson and Maria. Speedy and Bats are a tag team so they almost always work together on missions. But once something went wrong when they were dispatched with their team so they were exposed to radioactivity which granted them a superpower. Speedy was granted the power of "Mind Over Matter" and Bats was given a "Appearance Alteration", which are both sub-categories of Illusion Manipulation. For example, Speedy can make it so that the foe feels like they're drowning when they're actually not, and "Appearance Alteration" speaks for itself. Bats can camouflage herself or change her appearance. Should they be in a situation where they can't focus clearly to use these illusions, they're also highly skilled combat-wise and are rather handy with various firearms.
I'm writing myself last because we discussed my powers last in the MSN chat. For me I'd be connected to Tony in the sense that I'd be his biological daughter. I just think it'd be super cool to have a dad like him leave me alone. Granted, it's been a couple of years since the last time the Avengers assembled, so he and Pepper would've had me, respectfully. Part of this idea came from a post on Tumblr where it was somebody's headcanon that Tony would act in a similar manner Maes Hughes from Fullmetal Alchemist would in regards to his kid. He'd constantly show the picture to everyone and the usual response would be, "DAMN IT TONY WE'RE IN THE MIDDLE OF A BATTLE WE DON'T WANT TO SEE A PHOTO OF YOUR KID." The person wrote (as an example probably) his daughter's name as Victoria and since that is actually my name in real life, I went with it. BUT I DIGRESS...
Anyway, I'd have a lot of his traits such as his snark and genius intellect with narcissism included. But like momma Pepper I also worry a lot about people close to me. Other things are that I make sure everyone and everything is taken care of (most of the time) because I don't trust people do it themselves. Though because everyone else has all these badass powers, I actually feel inferior and therefore don't deem myself a hero, but I don't openly admit it. I also butt heads a lot with Tsuna, just like Tony and Steve do. Sashi helped me a lot with mine actually, so this is what we decided upon: I had complications with my heart so I wasn't exactly a healthy child. I envied virtually everyone with good health and wanted to be amazing like my dad, so I was like, "Well let's get a new one. If dad can live off it, so can I!" Basically, I have the arc reactor Tony has, except mine is on the chest plate, for obvious reasons. My heart in a sense becomes "mechanical" (imagine it as you please) and for it to be powered, it requires that. I also can't hear very well, almost to the point of being deaf, because a family vacation had been sabotaged, so I need hearing aides which basically restores this sense to it's normal capacity. It also allows me to translate any known language spoken by mankind, but I can't speak it back. For that I'd actually have to take language classes. Both operations were risky and because it's technology and can still be damaged, Tony gets overprotective of me even though I'm fine. I eventually get a suit like his, albeit a different color, because I want to be able to fight alongside everyone else and I'm going to make my handicap become my ace in the hole. Just like Tony doesn't like to be handed things, I don't like to be touched without permission, unless I ask for it.
I think that's about it. Other notes include Sashi and I fighting over Steve, but then I secretly ship him with Koondy. Then Sashi and I would butt heads over Thor but eventually get over it. Dad Tony wouldn't like it that I have this huge crush on Steve because I'd be like, "...so dad. Who's your friend." "Tori, you're younger than him by a few decades. I didn't raise you to be jailbait." I'd have an admiration for him since he was "sickly" like me but then enhanced, even thought it wasn't the same way I was. Sashi would call Thor a bishounen but I'd be so confused because I'd have no idea what the hell that is and I'd just call him a hunk of a man or a teddy bear with great hair who I would not mind hugging at any time whatsoever. Yeah.
THAT'S BASICALLY IT. Buuuuut, we need your input too! Tell us if you want things changed, like deleted or added! Also, no shipping with canonical characters because of the age difference. For that, Sashi and I decided to just create our own, but that one requires a group collaboration.
Edit 1: Speedy and Bats switch powers.