Mostly a reference for myself, so I can keep Ri's personal timeline consistent, as he differs from canon in a few ways.
~ Kingdom Hearts (first game occurs)
--> Roxas is 'born' and taken in by Xemnas and Organization XIII.
--> Vexen has already been engaged in studying the Heart (from Apprentice days), as well as making replicas.
~ KH ends
--> Organization XIII attempts to 'recruit' Riku and he tells them to fuck off.
--> Vexen decides (with Xemnas' permission) to try and create a replica of Riku, to try and harness his Dark power. There are many failures before he perfects the combination of an Artificial Heart and created body.
0 -- The Riku Replica is created in Castle Oblivion.
--> Because Vexen was lacking complete and necessary data, Repliku was only a bodily/physical copy of Riku, with no Memories (neither Riku's nor his own), and very little of the Darkness power.
----> Vexen takes it upon himself to educate Repliku, and oversees his basic development. Repliku, at this time, saw Vexen as a creator/mentor/father-figure and was very obedient towards him.
1~2 months -- Marluxia and Larxene
--> Marluxia uses his position as Lord of Castle Oblivion to 'train' Repliku more. This is when Larxene began physically abusing Repliku, eventually moving up to sexual abuse. Marluxia began his own abuse of Repliku, physically, sexually, and mentally.
2~3 months -- Master... Lord Marluxia
--> In a relatively short period of time (mostly because Repliku was already a blank slate), Repliku is trained to be completely subservient to Marluxia, much to Vexen's dislike.
--> Repliku is convinced by Marluxia that Repliku's feelings for him are 'love'. In reality it is more like Stockholm Syndrome. Repliku is still regularly abused by Larxene, and Marluxia's previous 'gentle' behavior becomes more vicious and cruel.
~ Chain of Memories (begins)
--> Sora, Donald, and Goofy (and Jiminy) enter the 1st Floor of Castle Oblivion.
--> Riku enters the 12th Basement of Castle Oblivion.
----> Vexen fights Riku and gathers the rest of the data he needs.
3~4 months -- The Riku Replica
--> Vexen 'completes' Repliku, giving him the power of Riku's that he lacked.
--> Namine is used to partially break Repliku's Heart, to give him Riku's personality and attitude.
----> At this point, Repliku is completely derisive and hostile to Riku and his fear of the Dark, using his own embrace of Darkness as the main turning point in Repliku being 'better' than Riku. He does have his own personality, though he is generally quiet and subservient.
--> Repliku fights Riku for the first time... and loses.
--> Larxene pushes Marluxia's agenda, and forces Namine to Break Repliku's Heart completely. Vexen allows this to occur, making Repliku betrayed by not only his 'father', but by his 'lover' (Marluxia) as well.
3~4 months -- Riku
--> CoM game canon
----> As Riku, Repliku has absolutely no Memories that are not Riku's. He does not remember his own few months of life, nor his relationship to the Nobodies.
--> Repliku (believing that he is Riku) fights Sora four times. He loses all four times.
----> Namine completely shatters Repliku's Heart to keep him from attacking Sora.
--> Repliku manages to 'pull himself together' using his own strength of will and the Promises he's made to help Sora fight Marluxia and protect Namine. He leaves Sora and Namine on the 12th Floor of Castle Oblivion.
----> At this point, Repliku is overwhelmed by the scattered Memories in his Heart and mind. He remembers his own time in Castle Oblivion side-by-side with Riku's Memories of childhood. He also remembers Marluxia and Larxene, and realizes that he'd been raped for a majority of his life (he previously did not know the concept). The dichotomy if Himself and Riku makes him completely unstable.
--> Goaded by Axel, Repliku absorbs Zexion's power, killing the Nobody.
--> Repliku fights Riku a second time... and loses.
4 months -- Repliku is killed by Riku.
~ Chain of Memories ends
~ Kingdom Hearts II begins
~ Kingdom Hearts II ends
~ 1 year after KHII -- Repliku wakes up in Castle Oblivion