Can I take Rengar's backstory and make a book out of it?

Not take the whole thing word by word but use the concept of it. ie a story of a beastman who was born and seen as the weakest of his family, constantly belittled by his father, leaves his tribe. Then becomes strong and comes back only to find his father is weak af and after killing him becomes the new chief of his tribe. The concept is so awesome, I just want to make a book out of it!

What I would take: -The beastmen concept. I think it's fitting that everyone's half beast in appearence. -The concept of the story as shown above. -Him having a pseudo mentor who, after getting annoyed by him, kicks him off a cliff to fend for himself (ngl that moment was bad ass).

What I would add: -Several hunts -Main character becomes mercenary? -potential subplot within the main character going on a mission that goes awry (meets his mentor again?).

What I would change: -Different names for obvious reasons (and I'm not talking about cheap chinese kock off game style and calling the main character Rengor or something) -No humans. Everyone's a beastman. Won't even have human looking beastment (like xayah/ahri/rakan etc.) -No magic. Everything is pretty primitive and therefore no vastaya related origin story. -No kha'zix like entity. There might be a hunting rival but not an enemy on the scale of khazix. Nor is there a supernatural force like the void. -The reason he leaves the tribe in the first place. I was thinking along the lines of him having an even weaker sibling. The main character is attached to this sibling but he/she is so weak that their father decides to kill him/her to 'set an example'. The main character is angry and scared (he is now officially the weakest of his bretheren) and decides to leave for that reason.

Why do I ask? I ask as I don't want to infringe any copyright. I also feel like it would be dishonest to not ask first considering the backstory is all riot's idea (even if legally I could do so). Also I would be interested if the community would be interested if I did make a book based on it (I could post chapters every so often on the boards for you guys to read). Finally I ask the boards (hopefully a rioter could respond) as I don't know who else to ask (does the support team even deal with this kind of issue?).