Okay everyone after doing some thinking I decided to make Sabo the leader of the Knights of D. Ren will be taken out as a result. Below are the reasons for the change.
Sabo is alive: I've decided to bring back Sabo and replace Ren with him. Originally the reason I created Ren was to replace Sabo. I felt that if Sabo was alive and with the revolutionary army, then he has to be the strongest and highest ranking member next to Dragon himself. However the problem with that is that the second strongest is suppose to be the leader of the Knights of D and you must be a D to be leader. Sabo however wasn't a D. But I found a way around that, make Sabo a D.
Sabo being a D: In this fic, Sabo's full name is Outlook D Sabo. His parents are not his actual parents, they are his uncle and aunt but not his parents. Sabo's father was a D while his mother was the sister of Outlook III, Sabo's supposed father. Both Outlook III and his wife hated Sabo's father and mother. Since Sabo's father was a D he was naturally very strong, popular and well liked. And Sabo's mother was a beautiful kind woman. They were both the exact opposite to Outlook and his wife and for that they both hated them and by extension their child Sabo himself. So they treated him badly and told them that Stelly who was their real son was adopted. They did this to make Sabo feel miserable. If your parents hate you so much, that they treat your supposed adopted brother better than you, then you must feel like trash. So in actually Sabo is the adopted son while Stelly is the real one.
Sabo's name: Sabo's full name is Outlook D Sabo. He is a D and Outlook by blood. The middle inital D is from his father and the last name Outlook is from his kind mother. So his full name is Outlook D Sabo.
Sabo's real parents: Sabo's father was a D and his mother Lady Outlook was the true head of the Outlook noble family. However she cast aside her nobility to be with Sabo's father. Because she was not only popular, beautiful and well loved, but also the true heiress of the Outlook family, her brother the snobbish Outlook III hated her and her husband. Outlook's equally snobbish wife hated them both as well. This is why they treated Sabo so badly. First he is not their actual child, Stelly is and secondly and more importantly, they despise Sabo's actual parents. The reason that Sabo is different from the two Outlook nobles is because he himself is not related to them at all (discounting the fact that they are his uncle and aunt).
Stelly: Stelly, Sabo's adoptive brother was said to have been adopted by the Outlook family from a family of higher noble status. This was a lie. Stelly is actually from the Outlook family and was given to the other family as an arranged family thing. They wouldn't give Sabo to the higher family since Sabo isn't really their son. They simply told Sabo that Stelly was adopted from the higher family to better lie about Sabo being they're real son to make him feel worse. They hate the fact that Sabo was the child of a D father and the beautiful lady Outlook.
Why did I change Sabo's parents: When I look at the differences between Sabo and his parents, they are just to big for me to ignore. So I decided to use that opportunity to give Sabo different parents with one being a D. That way I could make Sabo the leader of the Knights.
Connection between Luffy and Sabo: Both Luffy and Sabo have similar parentage although Luffy's is much higher. Luffy's father is a D and his mother a world noble. Similarly Sabo's father was a D and his mother a noble. However Luffy's parentage is much higher. Luffy's father Monkey D Dragon is the leader of the revolutionary army and strongest D and person alive while Luffy's mother is the highest class of noble, the Tenryuubito. Sabo's father is an unknown D and a regular noble. This similar heritage along with the fact that they are sworn brothers make them get along very well.
Sabo's looks: Sabo is almost identical to Ren in everyway. Same looks, same personality, same age (Sabo is about Ace's age), same devil fruit everything. The difference is that Sabo's hair is blonde while Ren's was golden and Sabo is human while Ren is an elf. However Sabo has the same long bishounen hair, same calm personality (which he had since he was a child) everything. The only difference between Sabo and Ren is that Sabo doesn't have golden hair or pointy ears since he is not an elf.
Why did I bring Sabo back: Well after some research into Sabo's past I found it weird that Sabo's parents would treat him so horribly. I mean even the tyrannical Tenryuubito at least cared for their own family. If you recall Saint Roswald became enraged when Luffy attacked his son Saint Charloss. But Sabo's parents didn't care about him even the slightest. So the answer was simple, they were not Sabo's parents. This meant that I could essentially do whatever I wanted about Sabo's parents. So I made his father a D, thus making Sabo the perfect leader of the Knights of D.
Sabo's loyalty to Dragon: Sabo is extremely loyal to Dragon. He never had real parents so when Dragon took him in, he saw him as a father figure. Add the fact that Luffy is his sworn brother, the entire Monkey D family is his family. Dragon is his sworn father and Luffy his sworn brother. His loyalty to Dragon is so great that he supports him fully despite his dark ambitions. He was corrupted by Dragon even more than Luffy. Luffy only spent about a month with Dragon and was already a teenager but Sabo spent years with him and he was subjected to Dragon's manipulation as a child, when his mind is most vulnerable.
Sabo not trying to save Ace during the War of the Best: Sabo wanted to save his sworn brother Ace but Dragon convinced him that it wasn't the right time to reveal the power of the Knights. Sabo was very reluctant but agreed.
The section in "Issues Explained, not a Chapter" devoted to the similarities between Sabo and Ren has been taken out. Appropriate changes have been made to "Profile of the Revolutionary Army." The same applies to all chapters where Ren appears in. Ren is changed to Sabo, no change has been made to the chapter content so you don't have to read them all over again.