I like this theory. It's kinda cool to see Riven as the female version of cloud
But... sorry to burst your bubble mael.
Riven started off as the name for the character who would be exiled from damacia fpr aiding in the escape of noxian prisoners who were to be executed. this brought to the idea for Riven The Exile. The idea was scraped but they still wanted to have the ide for a champion who would be disowned from their faction and wish to seek there redemption. Riven's designer Xypherous (also known for designing Lulu, Nautilus, and Orianna) Said that he took some inspiriation from Rurouni Kenshin when desiging Riven's new back story where she would be Noxian instead. As for her exile, he wanted it to be a bit like Aragorn's exile from Lord of the rings. In fact, Riven's story is a reminicent of Aragorn's, for he was exiled with a broken sword which was reforged to help defeat Sauron.
A related note, if anyone here is familiar with the Myst series, the second game is called Riven and the third is called Exile.