Garp and Dragon: their mysterious past revealed?
Monkey D. Garp
Garp is one of the most respected and the most powerful marines in the whole series.
“Garp the fist” – this is how enemies refer to him , this could mean that he has the strongest armament Haki.
Monkey D. Garp’s past
Garp doesn’t care about his rank in the marines as long as he isn’t an admiral because he doesn’t want to obay the Celestial Dragons he turned down promotions constantly
The future of the Marines
Back then Roger was a rookie there were the future stars of the marines Garp, Senoku, Zephyr and also Tsuru. But the monster trio back then was Garp “ The Fist” – Sengoku “The Buddha”- Zephyr “Black Arm” ( deceased ).
All 3 were given the chances to become admirals but Garp turned down his offer.
Zephyr left the marines to start neo marines.
Sengoku became a fleet admiral.
So these 3 were the strongest marines.
Tho later in the series Garp and Sengoku became a duo fighting Shiki the later Blackbeard Pirates.
Monkey D. Dragon
Speculation : Dragon was not a marine but he was working for the World Government with an unknown Alias because Dragon was investigating the World Government. Dragon got a high rank, within the Government he learned about their plans, everything they knew, but he dissapeared. Even Garp didn’t know what happened.
The Great Battle of Edd war
After this, Garp was seen turning down a promotion again, he joined Sengoku when he was going to investigate after saying “I’ll give you all the credit”, he was a carefree marine.
Speculation: Dragon was involved in the Edd War. This was the reason why Garp wanted to investigate the whereabouts of Dragon rather than what happened between Roger and Shiki.
Gol.D.Rogers Execution
After Roger was executed Dragon was seen in Logue Town. Garp would also be there but he wasn’t seen in the anime.
Speculation: last time Garp and Dragon met, Dragon explains why he dissapeared and about what he learned from the Government causing him to rebel against the World Government with the Revolutionary Army. Garp also doesn’t approve the ways of the Government so to not involve Garp Dragon cut all ties with Garp.
Portgas D. Ace 
Roger made Garp promise to protect Ace.
He hid Ace from his superiors ( not Sengoku, they seem to have a brotherly bond ) but Sengoku eventually revealed it to the world after his capture.
Ace’s death effected Garp as he wanted to kill Akainu after Ace died but Sengoku had to stop him.
Speculation: Garp wanted Ace to become a great marine because he believed in Ace to be safe where he was but Ace left. Later Ace realizes Garp’s efforts to keep him safe.
Fact: Sengoku was more worried about Garp than Whitebeard because Garp could have broken Ace out easy.
Sengoku said “don’t do anything stupid”
And Dadan also beated him up for not saving Ace. But Dadan didn’t know his situation at Marineford.
Monkey D. Dragon’s past
Dragon started the Revolutionaries after the death of Gol D.Roger.
Garp knew about the Revolutionaries because the last time Dragon and Garp was speculated to be at the same place was Lougue Town 22 years ago.
Monkey D. Luffy
Luffy was born 3 years after the start of the Revolutionaries ( speculation ). His mother’s whereabout or status is unknown but Ivankov stated that Dragon always faced east where he left Luffy.
Speculation: Dragon left Luffy right after he was born because of his status the world’s most wanted man and didn’t want the World Government to find out , Luffy could have easily been killed if the the Government found out. But when they revealed it, Luffy had a lot of powerful allies and was strong enough to defend himself and everyone who heard it went to shock.
Dragon would be ok with Luffy joining the Marines because Garp would be there and by the time Luffy could become admiral (just an alternative If luffy ever became a marine 0% chance ) Dragon would have overthrown the World Government and like Garp Luffy has his own way of justice but Luffy became a pirate meaning that Dragon didn’t have to worry about anything as he was trained by Garp along with Ace.
Start of the Revolutionary Army
Like I said Dragon started the Revolutionaries right after Roger’s death but he could have started with Bartholomew Kuma and Emporio Ivankov and has been recruiting solders for 22 years.
Key: Dragon would have had more than 500k ( just an estemate ) soldiers by now. Dragon could also have powerful unknown allies.
Why did dìDragon join the World Government ??
This is pure speculation but there is huge possbility of this:
– Garp , Dragon , Luffy all have a similar way of justice
Ok so when Dragon was young he saw what the Celestial Dragons did to the people of where he lived and as I said Dragon would never just let people with that much power do as they wanted.
So Dragon joined the Government to investigate and gather intel enough to overthrow them.
Most Wanted Man in the World
Before dissapearing from the world, Dragon stole critical information about the World Government with his authority angering the World Government after his betrayal.
Aftermath: Dragon would have the highest bounty , higher than the current yonko but lower than Roger.
Garp’s retirement
Garp left the marines after Akainu became fleet admiral and he’s no longer working in marine HQ.
All part of the plan ??
By part of the plan I said that because the Government would make Garp fight Dragon and this could never happen because they respect each other’s decisions as they went on their separate ways.
And this fight could possibly destroy the Marineford…again 
So to sum up
• Garp and Dragon worked for the Government
• Dragon was investigating the Government
• Dragon dissapeared with vital information and future plans of the Government
• Dragon reappeared in the Edd War causing Garp to go investigate
• They meet at Roger’s Execution
• Dragon starts the Revolutionaries
• Dragon leaves Luffy, and Garp takes care of Luffy and Ace
• Garp retires after the death of Ace
• Dragon makes his move (speculation)
*Theory by King of beasts kaido
