I've seen a few concepts on multi body champions, including a Mario and Luigi one that was deleted for some reason.
Hawker's was a first mate on a Noxian warship until it was sunk by the Great Pirate Gangplank. He survived the blast, and eventually washed up on a small island. There, he found an ancient golem from an ancient war, that became soul-bound to him. They now share vitality.
Hawker is bent on avenging his captain and crew, however the Noxian government did not see profit in assassinating Gangplank. So Hawker set out to find a ship, and assemble his own crew. He will do anything to kill gangplank, even piracy.
Stats and abilities
Hawker and Adarr are custom champion(s) in League of Legends.
Hawker and Adarr start with one rank in Twin Souls, and begins controlling Hawker.
I suggest reading Steel and Stone followed by Twin Souls before reading the rest of the kit.
It is most beneficial to build a mix of damage, and defense. There is no need to stack too much damage and too much defense as Hawker and Adarr benefit differently from defense and offence. Hawker benefits from damage far greater than Adarr and Adarr benefits far greater from defense than Hawker. Focus on crit chance items such as Infinity Edge and Youmoo's ghost blade for Hawker's damage. Focus on items that mix health with armor and/or Magic resistance for Adarrs defense.
Building only defense will leave you dealing very little damage, but Hawker will still be very vulnerable. Building only damage will also leave you vulnerable as Adarr's extra body makes it difficult to dodge skill shots without a creep wave.
While Hawker and Adarr would have very lack luster kits on their own. It is mastery of using their kits together, and switching between them that makes the difference between a good H&A player and a bad H&A player. Prolonged engages are not your strong suit. Fight just long enough to use Hawker's abilities, then disengage using Adarr's kit before leaping away with both. These combos can be hard to pull off at early levels. Level up Twin souls whenever possible as it reduces the cooldown between them, making it easier to switch back and forth as needed.
Leaping away with Give me a boost is often times the best way to disengage. Though it does leave Adarr vulnerable, he will gain bonus tenacity which can still help.
Hawker has medium length cooldowns, while he can engage quickly and dish out a lot of damage, he needs to peel back as his abilities fuel his damage capabilities.
Adarr has long cooldowns but his abilities have fantastic uses. He can poke, save hawker, and shove enemies away. He is good at applying CC and disengaging. His abilities are best used after Hawker's abilities are on cooldown. Do not waist his abilities.
In top lane you can control when to engage and disengage, using Adarr to keep enemies off of Hawker. Melee champions are very common in the top lane, and melee champions are H&A's easiest opponents, especially immobile ones such as Darius and Nasus.
In the jungle you can utilize H&A's passive to its extreme. Adarr will naturally shield you from jungle monsters making full use of his obscene tankiness, meanwhile Hawker can attack the minions. When ganking a lane, use Give me a Boost, followed by Protective Brotherhood to get near the enemy. Switch back to Hawker and begin attacking. Act like an assassin when engaging as you don't have the crowd control to give the kill to your ally.
In team fights using protective brotherhood to survive the initial engage is almost always recommended, think of it as a Pseudo-Zhonias. After they have closed in on you, you can use Hawker to deal as much damage to a carry as possible. After killing your target, Give me a Boost should be off of cooldown and can be used to get Hawker out of the engagement.
If Adarr tosses Hawker over a wall at you it might be the right time to kill him. Adarr will be unable to protect Hawker until it makes its way around the entire wall. Baiting out Hawkers Give me a Boost is often the best way to kill him.
Applying crown control to either one is rewarding. Even something as tanky as Adarr can be killed when properly kited. It wont be able to dodge skill shots when it isn't being controlled by the enemy player.
Focus and burst Hawker when possible. He is squishy.
This is a good time to shut them down. As their extreme tankiness stems from items they will be most easily killed at this stage of the game. They require level three to do full combos including their truly tricky engages and disengages, and even that will be difficult without ranks in Twin Souls.
Check his build. By this time he should have one to one and a half items. Are they more tanky or are they have more damage? If they are tankier, you don't have to be that afraid of Hawker as his damage is largely dependent on scaling. If they have more damage then durability, unleash hell on the bigger easier hit target: Adarr. Adarr is easily hit as it tries to stay in between hawker and you.
Dueling with them is always a game of "how do i get to Hawker, without hawker getting to me". Its similar to fighting any assassin paired with a tanky support. Sometimes the support is the solution. The two of them share health, making it useful to poke Adarr on occasion. You might consider building armor penetration against good H&A players.
(This is the largest part of the lore sorry)
Hawker lifted his face from the wet sand. He thanked the gods he had washed up on the shore. Still shivering from the cold and soaked in salt water, Hawker crawled up shore to get to dryer sand, and to get his feet out of the ocean. After about an hour in the sun the majority of his clothes were dry and his body heat had returned.
Hawker explored the small island, eventually finding some kind of stone structure. It was small, and had no door, but it had stairs that led downward. After creating a make-shift torch, Hawker drew his sword and descended into the structure.
The stairs spiraled into the ground for a surprisingly long way, especially for being on an island. Hawker estimated he was at least 50 feet under the ground when he found a solid floor. The torch he had created couldn't illuminate the whole room, so he stayed close to the left wall as he explored the place. He came across large stone objects, almost human in shape, broken and scattered across the floor.
He spun, taking in the shapes, and walked backward a short distance. He bumped into something. He spun on his heel bringing his Rapier to bare with whatever it was. One to the stone shapes was standing before him, un-moving, largely covered in moss with few exceptions including its head. Hawker approached the stone behemoth, and sheathed his sword as he figure it was inactive.
It stood at least four feet taller than him. He ran his hands along its moss covered arm. "It feels like....", he muttered to himself. He dug his nails into the moss and tore a chunk of it from the arm. "It is..." he stated, astonished by the crystal markings on its arm.
"Clearly from a rune war, but not the most recent one." He brushed his fingers over it before turning his back on it. "I'm going to need to get back up their. With that thing here I can't use this place as a shelter," He reasoned to himself.
Hawker turned and walked toward the faint light still coming from the stair well. He was about half way their before a blue glow from behind caught his attention. He froze in place, being sure not to move too much. After a few seconds a low rumble began shaking the stone walls. Hawker turned his head enough to see the creature out of the corner of his eye.
The creatures leg shook and lurched forward, flinging moss from its joints. It opened its mouth and let out a low grumble "AAaaaaAAAawwwddaaawwRRRR!!!"
Hawker sprinted to the exit and began climbing the stairs as fast as he could. Loud booms rang out from below him. It must have been running after him. Hawker reached the top and tripped, scraping his right palm on several rocks as he caught his fall. He heard the beast right behind him, so he rolled onto his back and scrambled backward away from the creature. It walked to him slowly, and carefully. "Aaddaawwrrrr" It rumbled extending its right hand as if to help him up.
Hawker, still in shock the creature hadn't killed him, hesitantly extended his own hand to accept the offer, when he noticed that there were deep scuffs marking the golem's palm. To Hawker's astonishment, they matched the scrapes across his own hand.
"There is an issue in the Gaurdian's Sea that can no longer be ignored!" Hawker yelled at the secretary.
"I am sorry sire," began the stern, pale skinned secretary" but General Krosive will not see you again. He has already told you that it would not be profitable to..."
"Profit has nothing to do with it," Hawker snapped, "We need to secure that area for Noxus' power, to set an example."
"Debating with me will do no good. I am simply the Generals Secretary."
Hawker responded with an angry grunt and turned to leave, only to see Darius entering the hall through a door at the far end. The legendary soldier was at least a foot taller than Hawker and never seen without his armor and signature axe.
"Are you first officer Hawker?" Darius had caught site of him and was storming towards him. "We have received reports that you found a war relic. If this is true you need to reveal its location immediately."
"I'm sorry Commander Darius but I have no idea what you are talking about."
How do two bodies work
Both bodies benefit from all passives from items, elixers, dragon, baron, smite buffs and jungle monster buffs.
Both bodies radiate auras (such as legion) but these auras never overlap with just Hawker and Adarr (Sunfire Cape, Frozen Heart ETC)
Active abilities are centered on the champion that is being controlled.
EXAMPLE: Bilgewater cutlass' range will stem from hawker so long as you are controlling hawker and will grant the movement speed to hawker only. The same is true for Adarr if you are controlling him.
Buffs from allied champion abilities and item effect H&A separately as well, only helping the target hit.
EXAMPLE: Adarr uses Yomuu's Ghost Blade to gain movement speed, however Nami uses Tidecaller's Blessing on Hawker. Adarr only benefits from Yomuu's ghost blade, and Hawker only benefits from Nami's Tidecaller's Blessing (and surging tides).
These buffs remain on the original body, and do not move if control is swapped.
GENERAL Slow scaling on Shoulder Artillery fixed. Give me a boost reworded for clarity. New section for specific details on how two bodies work added.
ADARR Adarr's cooldowns set to 15 from 22. Damage of Shoulder Artillery increased by 25 at all ranks. 110 / 145 / 180 / 215 / 240 from 85 / 110 / 145 / 180 / 215
HAWKER Damage scaling on Silver footwork increased to 120% bonus AD from 40% AD.
Adarrs cooldowns would be too oppressive at 22. His cooldowns are still high (15), so his abilities should deal nice damage at least in the early game. Especially as they are hard to land.
Hawker's late game power was lacking. The damage is triggered after committing to 4 auto attacks, and he should be rewarded for that.